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Vapor's Comprehensive Guide to Odor Control and Reduction Methods
Abstract:
While searching through websites and forums and PDF's on information on odor control and reduction; I thought to myself "Gee, someone should really put something a little more comprehensive together that actually lists some of the methods and how they actually work instead of having to look through 50 different websites." I did a few searches on AFN for this information and while I found a few great posts; I wanted to tie everything together like the perfect rug in a living room does.
This is my attempt at that. I'm not a scientist; I'm just a guy who likes to read a lot and put things together. I am not the mastermind behind a lot of this information so let the credit fall to those brilliant minds whose research helped me base this guide on. I did write this guide, however, and this is my interpretation of my findings in what I hope is easy to read and discern facts from. I hope the information is as accurate as possible; and if you find anything misinforming or that needs to be correct; please constructively advise me so I can change it!
I'm putting this guide together to:
Chapter 1: Why do my plants smell?
Terpenes and Terpenoids
Marijuana plants, as well as many other plants, produce organic compounds called terpenes. Terpenes are a major component of resin, often very strong smelling, and sometimes act as a protective function for the plant.
When terpenes are modified through chemical processes (oxidation or reduction) they become terpenoids. Plant terpenoids are primarily sought after for their fragrant aromatic qualities, especially when it comes to essential oils (terpenes and terpenoids are a large basis of aroma therapy.)
It is thought to be believed that the amount of terpenes present in marijuana resin affects the potency of the THC in the resin. Since terpenes are secreted by the marijuana plant's glandular trichomes; it is important to try to increase trichome production through good gardening practices (as you will find in other guides on this site.)
Terpenes are also highly volatile and evaporate quickly. The marijuana plant constantly produces terpenes, but heat and light also destroys them. This is why it's important to keep temperatures at a constant (within range for the plant) in your growing space. This is also why it is advised to harvest your plants early in the morning (or before lights on.)
The curing and drying process can also affect how well terpenes are preserved. This is why you can have some dank smelling herbs while growing; then botch (accidentally of course) your curing/drying process and have herb that doesn't have much of a smell (or a weird smell.) Heat and excessive or rapid evaporation can cause terpene reduction in your buds. This is why slow drying/curing is often preferred over some faster conventional methods.
Terpenes can vary greatly depending on their environment and climate. The same plants grown in one substrate may produce terpenes different than if they were grown in another type of substrate. The same goes with fertilizers; one type of fertilizer product line may cause different terpene production than another fertilizer line.
There are over 120 different kinds of terpenes that can be produced by marijuana in small trace amounts or large quantities. Here are some examples of common terpenes found in marijuana. This is a list taken from a website:
-Borneol- menthol, camphor, pine, woody."* Can be easily converted into menthol. Found in Cinnamon and Wormwood."* It is considered a “calming sedative†in Chinese medicine. It is directed for fatigue, recovery from illness and stress.
-Caryophyllene- "spicy, sweet, woody, clove, camphor, peppery."* Found in black pepper(15-25%), clove(10-20%) and cotton(15-25%). It binds weakly to CB2 receptor."* As a topical it is one of the constituents of clove oil, an anti-inflammatory and analgesic treatment for toothache."* In high amounts, it's a calcium and potassium ion channel blocker."* As a result, it impedes the pressure exerted by heart muscles."* Since THC does not have a smell, drug dogs are trained to find one, very smelly molecule called Caryophyllene-epoxide!
-Cineole/Eucalyptol- "*spicy, camphor, refreshing, minty."* Found in rosemary, eucalyptus. "*It is used to increase circulation, pain relief and easily crosses the blood-brain-barrier to trigger fast olfactory reaction. Eucalyptus oil is considered centering, balancing and stimulating. It is possibly the stimulating and thought provoking part of the cannabis smoke stream.
-Delta3Carene-"*sweet, pine, cedar, woodsy, pungent."* A constituent of rosemary, pine and cedar resin. In aroma therapy, cypress oil, high in D-3-carene, is used to dry excess fluids, tears, running noses, excess menstrual flow and perspiration. It may contribute to the dry eye and mouth experienced by some marijuana users.
-Limonene-"*citrus (orange, tangerine, lemon, and grapefruit), rosemary, juniper, peppermint."*"*Repulsive to predators."* Found in the rinds of many fruits and flowers."* With the presence of other certain terpenes, Limonene can be an anti-bacterial, anti-fungal, anti-depressant and anti- carcinogen. "*It can synergistically promote the absorption of other terpenes by quickly penetrating cell membranes. The result can be increased systolic blood pressure."* Since Limonene is such a potent anti-fungal and anti-cancer agent, it is thought to protect against aspergillus fungi and carcinogens found in cannabis smoke streams!"*"*
-Linolool- "*floral (spring flowers), lily, citrus and candied spice."* Possesses anti-anxiety and sedative properties (also in lavender)."*"*"*
-Myrcene- "*clove like, earthy, green-vegetative, citrus, fruity with tropical mango and minty nuances."* The most prevalent terpene found in most varieties of marijuana, it is also present in high amounts in Mangos, hops, lemon grass, East Indian bay tree, verbena and Mercia. "*Myrcene is one of the most important chemicals used in the perfumery industry. Because of its pleasant odor, it is occasionally used directly. "*It's a building block for menthol, citronella, and geraniol. "*It possesses antimicrobial, antiseptic, analgesic, antioxidant, anti-carcinogen, anti depressant, anti-inflammatory, and muscle relaxing effects. "*"*Myrcene affects the permeability of the cell membranes, allowing more THC to reach brain cells.
-Pinene-"*Alpha: pine needles, rosemary"*Beta: dill, parsley, rosemary, basil, yarrow, rose, hops, the familiar odor associated with pine trees and their resins. It is the major component in turpentine and is found in many other plant essential oils including rosemary, sage, and eucalyptus. "*Pinene can increase mental focus and energy, as well as act as an expectorant, bronchodilator (the smoke seems to expand in your lungs), and topical antiseptic. It easily crosses the blood-brain barrier where it inhibits activity of acetylcholinesterase, which destroys acetylcholine, an information transfer molecule, resulting in better memory. It may counteract THC's activity, which leads to low acetylcholine levels."* Largely due to the presence of pinene, rosemary and sage are both considered “memory plants.â€"* Concoctions made from their leaves have been used for thousands of years in traditional medicine to retain and restore memory.
-Pulegone-"*mint, camphor, rosemary, candy."* It is implicated in liver damage in very high dosages. It is found in tiny quantities in marijuana."* Pulegone is an acetylcholinesterase inhibitor. That is, it stops the action of the protein that destroys acetylcholine, which is used by the brain to store memories."*
-Sabinene –"*Found in oak trees, tea tree oil, black pepper and is a major constituent of carrot seed oil."*"*
-Terpineol-"*floral, lilac, citrus, apple/orange blossoms, lime. "*It is a minor constituent of many plant essential oils. It is used in perfumes and soaps for fragrance."* It reduces physical motility 45% in lab rat tests… Couch-lock effect? "*
So in a nutshell, your plants produce terpenes as a byproduct of their resin glands (in this case; the trichomes.) Terpene production is a defense capability of your plant which helps ward off predators (some herbivores,) and can also be produced in response to physical stress that may be caused by living or nonliving things (humans, heat, light, environment, etc.) These are the primary source of the smell of your plants and there are many variables that can affect their production, physical and chemical qualities, and preservation.
Here is a more detailed example of how marijuana terpenes are measured in a laboratory environment.
http://www.srigc.com/Terpene Method.pdf
Chapter 2: So how do I help with the smell?
Carbon Filters
What is activated carbon? Activated carbon is charcoal that's been treated with oxygen to open up millions of pores between the carbon atoms. This process occurs at a very high temperature (around 1800 degrees Fahrenheit of steamed heat.)
Carbon filtering is a method of filtering that uses a bed of activated carbon (charcoal) to remove contaminants and impurities using chemical absorption. Activated carbon is very effective at removing the VOC's (Volatile Organic Compounds) produced by your plants. For intents and purposes, this guide will focus on air filtering.
Basically, each particle or granule of activated carbon provides a surface area full of pores for impurities to be exposed to. As the impurities passes through the carbon, they get absorbed (trapped) in the porous holes through chemical attraction. The more surface areas exposed, the better chance of filtration (which is why you want your carbon to be crushed to expose more surface area) because the larger surface area exposes more bonding sites. Particle sizes that can be removed by carbon filters range from .5 to 50 micrometers. As time goes on; the bonding sites on the carbon begin to fill up and the effectiveness of the odor reduction decreases. Once all the bonding sites on the activated carbon are full; the filtration ceases to be effective (and the carbon needs to be replaced.)
Here's a fun factoid; 1 pound of activated carbon contains the surface area of over 100 acres!
The efficiency of a carbon filter depends on several things:
The Carbon Scrubber
The most common type of air filtering for growing is probably the carbon scrubber. These usually come in a 4" or 6" duct fitting variety, capped on one end with the duct fitting on the other end. These are usually cylindrical in shape; with the middle (core) being open air and the outer core being filled with activated carbon with pores all over the metal work of the outside and inside ring.
A fan is fitted either to the carbon scrubber itself or somewhere inline the ductwork leading from the scrubber. The fan must be appropriately rated to the CFM requirement of the scrubber, NOT the area of the grow room (if it happens to work out that it does both; pat yourself on the back.) The reason for this is that you need adequate air flow for the air to pass through the filter. The longer the contaminants are exposed to the filter media; the better the absorption.
That being said; you have to consider a few things here:
You need a fan with enough CFM to adequately suck air through the filter. Imagine the carbon chunks not being in there for a second and the fan running. Not a lot of resistance to sucking in the air, right? Now, fill that same void with crushed carbon, and suddenly the fan is working harder (which produces more heat as a byproduct) and working at a diminished rate.
I personally use a LEDWholesalers 6" Carbon Scrubber (rated for 470 CFM) with a Hydrofarms 400 CFM fan and it works quite well in my tent (4 foot by 4 foot by 7 foot.) If there's not enough CFM; you are not going to be sucking much air through the filter; decreasing the effectiveness of the scrubber. If you have too high of a CFM rating, you will be pushing air through so fast that it's not having time to allow those molecules of the impurities to cling on to the carbon.
You should always have your fan sucking air through the filter; not blowing air through it. I'll explain why:
The inline fan draws air into the chamber of the carbon scrubber by blowing air out of it. Drawing air in is better than blowing air in because it doesn't produce as much turbulence inside, which in turns allows for greater control of the airflow through your ductwork. Why should you care about turbulence? The airflow created by the fan on the scrubber is already fairly turbulent due to how the fan blades are in motion and by design of the fan blades. Turbulence is the swirling of air (as in vortices.) Vortices occur on the length of the fan blade and at the blade tip as the blade moves through the air. As the speed increases on the fan, there is more turbulence created and the sound levels increase as the vortices increase.
Blowing air causes more turbulence than sucking air does, and depending on where your fan is in relation to the scrubber; that turbulence can greatly diminish the CFM capability of the fan.
Sucking air through the filter also offers more advantages. By sucking air through the filter, you are creating a negative air pressure space inside the carbon scrubber. Negative air pressure is good because it keeps those odor molecules from escaping the scrubber once they are in there. The extra benefit is, depending on the size of your grow tent/space; you can possibly achieve negative air pressure inside the growing space; which on a tent would cause the inside walls to suck in slightly. This is a good thing. This means you are sucking more air through your scrubber than you are actually pushing (from your inline intake fans) into the tent. This causes not only those odor molecules to more effectively stay trapped inside your tent (as in, less likely to leak out through zipper holes, pin holes, passive air intakes, etc, but also gives the scrubber more time to suck them up for filtration.
On top of all that; most scrubbers come with a pre-filter on them. This is usually a white fabric loop that slips over the exterior of the scrubber. This should ALWAYS be on your carbon scrubber. It filters out larger micron particles (like dirt and dust) and keeps them from coating your activated carbon. Remember, carbon works at a diminished rate when it gets covered as there are less and less bonding points for the chemical absorption to happen. The pre filter makes sure the big stuff that doesn't need to get filtered stays out and only lets the smaller, smelly molecules through. If you were to push air through the filter; you are effectively coating the insides of the carbon with EVERYTHING that's in the air (and blasting the excess to your pre filter inside out.) Most pre-filters are machine washable (or wash by hand), and tumble dry on low heat in the dryer.
That's not to say you can't push air through a carbon filter and have it not work. I know for a fact there are several growers on here that use that same and very setup. What should be noted though; sucking air through does in fact provide the most efficiency for the scrubber and is also backed up scientifically (if that sort of thing floats your boat.)
Can I clean and reuse my carbon?
I've been reading a lot about this lately and the short answer is “sort of but the time invested versus just buying some new activated carbon isn't worth it†and the long answer is more of what you'll read below.
The Organic Materials Review Institute (OMRI) has produced a paper on Activated Carbon processing which includes the following:
"Carbon can be reused if the adsorbed substances are removed. This process is known as 'regeneration.' Simply heating the spent carbon at a given temperature for an adequate length of time can regenerate activated carbon to the point where it can be reused for tertiary wastewater treatment (thermal regeneration) (Mine Safety Appliance Corp., 1970). Thermal regeneration inevitably results in the loss of carbon (Battelle, 1970). Also, thermal methods may not be the most efficient, inexpensive, or reliable method, so a number of solvents, acids, and alkalis may be employed to remove the adsorbed substances. These include such things as carbon tetrachloride, hydrochloric acid, hydrogen peroxide, potassium hydroxide, sodium hydroxide (Mine Safety Research Corp., 1970). Optimization of the regeneration process depends on the substances adsorbed as well as the structure of the activated carbon."
The problem with carbon regeneration is the removal of those volatile organic compounds once they've bonded with the carbon. The fastest way is through high temperature steaming (around 1800 degrees Fahrenheit from what I gather; although I've read some reports that say around 800 degrees may burn them off.)
The other methods involve using chemicals to break down the molecules before applying heat (which may attribute to needing a lower heat level if they've been chemically washed.)
Testing the efficiency of regenerated carbon is also very difficult. You can google a lot of web sites of growers that say "oh yeah I totally baked and reused my carbon" and maybe there's some merit to it; but I prefer to err on the side of science and it just seems to be out of the reach of most conventional people.
At this point though; unless you want to mess with chemicals on something that costs a few bucks online or at the pet store; or unless you own a furnace or heating device that can produce that much heat, it's really not worth it. In my humble opinion; if you want to try to extend the life of your carbon; take a hammer to it. Smash it in more pieces; which will expose more surface area and bonding sites. Otherwise; pony up the dough; because the time spent on doing a "home brewed" regeneration could have been time spent on making the money to get brand new manufactured carbon. Just my two cents though; take that last bit with a grain of salt if you are feeling like trying something new
Essential Oils
This was taken from the US Library of Medicine National Institutes of Health:
"Recent studies of olfactory blocking have revealed that binary odorant mixtures are not always processed as though they give rise to mixture-unique configural properties. When animals are conditioned to one odorant (A) and then conditioned to a mixture of that odorant with a second (X), the ability to learn or express the association of X with reinforcement appears to be reduced relative to animals that were not preconditioned to A. A recent model of odor-based response patterns in the insect antennal lobe predicts that the strength of the blocking effect will be related to the perceptual similarity between the two odorants, i.e. greater similarity should increase the blocking effect. Here, we test that model in the honeybee Apis mellifera by first establishing a generalization matrix for three odorants and then testing for blocking between all possible combinations of them. We confirm earlier findings demonstrating the occurrence of the blocking effect in olfactory learning of compound stimuli. We show that the occurrence and the strength of the blocking effect depend on the odorants used in the experiment. In addition, we find very good agreement between our results and the model, and less agreement between our results and an alternative model recently proposed to explain the effect."
What are essential oils?
Essential oils are liquids extracted from plant matter by methods of pressing, solvent extraction, or steam distillation. The liquids are naturally occurring organic oils that come from things like seeds, leaves, and flowers to name a few. The oils are then redistilled or refined down to reduce unwanted materials in the final product.
Essential oils are made up of (wait for it...!) terpenes, esters (like ethyl acetate, the most common ester found in wines,) aldehydes (formaldehyde is an aldehyde,) ketones (fructose and acetone are examples of ketones,) phenols (like carbolic acid, a smelly phenol used for mild antiseptics,) oxides, and alcohols.
These oils also contain trace elements, which give the oils its character and enhance the ability to blend with other oils. These trace elements give the oils the unique characteristic ability of odor neutralization. When multiple trace elements are combined they work in synergy with each other which improves the effectiveness and range of application.
How do essential oils work?
Essential oils evaporate easily, infusing the air without leaving residue behind (highly volatile.) They do not react with odor causing chemicals/particles to remove them from the air. This means that unlike a carbon scrubber, they do not trap molecules and confine them. This also means they will do nothing for filtering out possibly hazardous chemicals/molecules (hopefully you are not working with anything that causes those in the first place.)
Essential oils are different than deodorizers (which just mask the smell.) Essential oils behave similar to a solvent. For example, picture the odor causing molecules as a solute (a component of a solution that is dissolved in the solvent.) The essential oils are diffused into the air through a method that optimizes absorption (process by which a fluid is dissolved by a liquid or a solid) and adsorption (process in which atoms, ions or molecules from a substance (it could be gas, liquid, or dissolved solid) adhere to a surface of the adsorbent.) If you get the two mixed up; that makes two of us. J
Things that affect absorption/adsorption:
The essential oils physically combine with the odorous material to form a new physical compound. The new combination should have no odor. That would be great if all conditions were 100% ideal, but certain odor molecules are heavier than others and are harder to neutralize (specifically in this case, hydrocarbons.) Many terpenes are hydrocarbons, but oxygen-containing compounds such as alcohols, aldehydes or ketones (terpenoids) are also found. That's not to say it won't neutralize the odors; just that those hydrocarbons have bigger boxing gloves on when it comes to combatting the odor molecules. The ultimate goal of the essential oil is to trick the human olfactory system (your sniffer) into not smelling something that is there. Success is based on not sensing any unpleasant odor in the air.
There are some things to keep in mind about essential oils. Not all essential oils are created equally. There are a very limited numbers of these oils effective for the process of odor neutralization. The effectiveness depends on how well the oils are chosen and blended to effect the correct chemical or physical reaction with odorous compounds. In short, this means you don't want to just start infusing just any essential oils into the air to try to combat marijuana odors. There are many essential oils that serve mostly as fragrances and used in perfume scents.
What's an example of an essential oil product?
ONA Gel
I'm sure if you spend any amount of time in searching for odor control methods for marijuana, you've probably stumbled across a product called ONA (Odor Neutralizing Agent.) ONA is a liquid based mixture of essential oils. It's non-toxic and environmentally safe. It's safe for your babies, it's safe for your doggies, it's safe for you. It's a green product. That said, that doesn't mean you should go sticking your nose into a jar of concentrated soaked ONA gel. That doesn't mean you should grab blobs of gel and roll it around in your hands. That doesn't mean you should eat the stuff or put it in an area kids or pets can eat. You shouldn't do that with almost ANY essential oils. You can find the MSDS (Material Safety Data Sheets) on their product website (MSDS sheets are excellent sources of information for products of this nature; I use them all the time in my work.)
I'm picking this particular product for it's essential oil use and because I've personally used it on a few grows with a great deal of success. If you do a quick search on AFN however; you'll see others were not as lucky. I've also read quite a bit of misinformation on here about this product; so I hope to clear up a few things about it (and no I'm not a spokesperson or work for them; I'm just a guy who tries stuff and if it works, spreads the word.) I've been wondering how some people have not had success with it while myself (and others) seem to love it.
Here are some product flaws of both right out of the box (see? I'm not totally biased here :smoke: ) Essential oils are most effective with a method of dispersion to allow them to mix with the odorous compounds. Neither the ONA block or the ONA gel quart jars have a method of dispersion other than open air, which relies on natural air movement or fans of some kind. The containers must also be placed in an area size appropriate to the container. If you place a quart jar in your living room and expect amazing results, you're going to be sorely disappointed. I use these in the bathroom (on top of the john) and next to litter boxes. Even without dispersion; they are close enough in proximity to react with the odorous compounds produced by the litter box and my *ahem* toilet.
I've used ONA quart jars in a 3 foot by 2 foot by 5 foot grow tent and had amazing results with a small 6†clip on fan blowing on the open mouth of the jar. No smell on the outside; curiously fresh smell of “linen†scent on the inside. I've used ONA quart jars on a 4 foot by 4 foot by 7 foot tent with a massive amount of autoflowers inside (again with a fan blowing on it for dispersion.) It helped with the smell immensely (but ultimately used the combination of a carbon scrubber and the ONA to kick the smells butt.) Hopefully that gives you an idea of what kind of limitations that particular design has based on volume. There are larger volumes of ONA product that you can buy (for more commercial applications), but considering the limitations of essential oils (they bond with the odorous compounds, not destroy them,) your needs and mileage may vary.
To address the people that claim it flat out didn't work; I think there are multiple possibilities of why not. Did they take measures to properly disperse the ONA? Is the ONA right next to a powerful exhaust fan that's pulling those same odor absorbing molecules right into the exhaust/scrubber? Is the ONA product of the right size for the dimensions of the grow room? And most important to point out is that essential oils (not ONA specifically) can only bond with certain carbons and hydrocarbons. Every marijuana plant out there produces different types of terpenes/terpenoids at different quantities. It's entirely possible (and feasible) that the essential oils in ONA may indeed NOT be bonding with the terpenes being produced by your plant!
There! I said it! ONA may in fact not work for your plants not based solely on the product design of mixture of essential oils, but in fact by the genetic design of your plant! Consider that a limitation of essential oils (they are not universally great at bonding with anything and everything.)
That said, I would still recommend at least trying it out as a supplement to your odor control. If one technique proves to be very useful; surely other proven techniques combined will prove to be of even more use.
COMING SOON!
Deodorizers
Ionizers
I want to say thank you for the read if you managed to get this far! I plan on updating the guide with a more in depth look at deodorizers and ionizers that are used in growing, as well as updating the guide with some pictures for more visual stimulus!
Abstract:
While searching through websites and forums and PDF's on information on odor control and reduction; I thought to myself "Gee, someone should really put something a little more comprehensive together that actually lists some of the methods and how they actually work instead of having to look through 50 different websites." I did a few searches on AFN for this information and while I found a few great posts; I wanted to tie everything together like the perfect rug in a living room does.
This is my attempt at that. I'm not a scientist; I'm just a guy who likes to read a lot and put things together. I am not the mastermind behind a lot of this information so let the credit fall to those brilliant minds whose research helped me base this guide on. I did write this guide, however, and this is my interpretation of my findings in what I hope is easy to read and discern facts from. I hope the information is as accurate as possible; and if you find anything misinforming or that needs to be correct; please constructively advise me so I can change it!
I'm putting this guide together to:
- Help promote good odor control and awareness involved with growing
- Explain some of the "what's" and "why's" of odor generation
- Help explain some common misconceptions about the technology used with odor control
- Educate growers on some of the odor control methods available to them
Chapter 1: Why do my plants smell?
Terpenes and Terpenoids
Marijuana plants, as well as many other plants, produce organic compounds called terpenes. Terpenes are a major component of resin, often very strong smelling, and sometimes act as a protective function for the plant.
When terpenes are modified through chemical processes (oxidation or reduction) they become terpenoids. Plant terpenoids are primarily sought after for their fragrant aromatic qualities, especially when it comes to essential oils (terpenes and terpenoids are a large basis of aroma therapy.)
It is thought to be believed that the amount of terpenes present in marijuana resin affects the potency of the THC in the resin. Since terpenes are secreted by the marijuana plant's glandular trichomes; it is important to try to increase trichome production through good gardening practices (as you will find in other guides on this site.)
Terpenes are also highly volatile and evaporate quickly. The marijuana plant constantly produces terpenes, but heat and light also destroys them. This is why it's important to keep temperatures at a constant (within range for the plant) in your growing space. This is also why it is advised to harvest your plants early in the morning (or before lights on.)
The curing and drying process can also affect how well terpenes are preserved. This is why you can have some dank smelling herbs while growing; then botch (accidentally of course) your curing/drying process and have herb that doesn't have much of a smell (or a weird smell.) Heat and excessive or rapid evaporation can cause terpene reduction in your buds. This is why slow drying/curing is often preferred over some faster conventional methods.
Terpenes can vary greatly depending on their environment and climate. The same plants grown in one substrate may produce terpenes different than if they were grown in another type of substrate. The same goes with fertilizers; one type of fertilizer product line may cause different terpene production than another fertilizer line.
There are over 120 different kinds of terpenes that can be produced by marijuana in small trace amounts or large quantities. Here are some examples of common terpenes found in marijuana. This is a list taken from a website:
-Borneol- menthol, camphor, pine, woody."* Can be easily converted into menthol. Found in Cinnamon and Wormwood."* It is considered a “calming sedative†in Chinese medicine. It is directed for fatigue, recovery from illness and stress.
-Caryophyllene- "spicy, sweet, woody, clove, camphor, peppery."* Found in black pepper(15-25%), clove(10-20%) and cotton(15-25%). It binds weakly to CB2 receptor."* As a topical it is one of the constituents of clove oil, an anti-inflammatory and analgesic treatment for toothache."* In high amounts, it's a calcium and potassium ion channel blocker."* As a result, it impedes the pressure exerted by heart muscles."* Since THC does not have a smell, drug dogs are trained to find one, very smelly molecule called Caryophyllene-epoxide!
-Cineole/Eucalyptol- "*spicy, camphor, refreshing, minty."* Found in rosemary, eucalyptus. "*It is used to increase circulation, pain relief and easily crosses the blood-brain-barrier to trigger fast olfactory reaction. Eucalyptus oil is considered centering, balancing and stimulating. It is possibly the stimulating and thought provoking part of the cannabis smoke stream.
-Delta3Carene-"*sweet, pine, cedar, woodsy, pungent."* A constituent of rosemary, pine and cedar resin. In aroma therapy, cypress oil, high in D-3-carene, is used to dry excess fluids, tears, running noses, excess menstrual flow and perspiration. It may contribute to the dry eye and mouth experienced by some marijuana users.
-Limonene-"*citrus (orange, tangerine, lemon, and grapefruit), rosemary, juniper, peppermint."*"*Repulsive to predators."* Found in the rinds of many fruits and flowers."* With the presence of other certain terpenes, Limonene can be an anti-bacterial, anti-fungal, anti-depressant and anti- carcinogen. "*It can synergistically promote the absorption of other terpenes by quickly penetrating cell membranes. The result can be increased systolic blood pressure."* Since Limonene is such a potent anti-fungal and anti-cancer agent, it is thought to protect against aspergillus fungi and carcinogens found in cannabis smoke streams!"*"*
-Linolool- "*floral (spring flowers), lily, citrus and candied spice."* Possesses anti-anxiety and sedative properties (also in lavender)."*"*"*
-Myrcene- "*clove like, earthy, green-vegetative, citrus, fruity with tropical mango and minty nuances."* The most prevalent terpene found in most varieties of marijuana, it is also present in high amounts in Mangos, hops, lemon grass, East Indian bay tree, verbena and Mercia. "*Myrcene is one of the most important chemicals used in the perfumery industry. Because of its pleasant odor, it is occasionally used directly. "*It's a building block for menthol, citronella, and geraniol. "*It possesses antimicrobial, antiseptic, analgesic, antioxidant, anti-carcinogen, anti depressant, anti-inflammatory, and muscle relaxing effects. "*"*Myrcene affects the permeability of the cell membranes, allowing more THC to reach brain cells.
-Pinene-"*Alpha: pine needles, rosemary"*Beta: dill, parsley, rosemary, basil, yarrow, rose, hops, the familiar odor associated with pine trees and their resins. It is the major component in turpentine and is found in many other plant essential oils including rosemary, sage, and eucalyptus. "*Pinene can increase mental focus and energy, as well as act as an expectorant, bronchodilator (the smoke seems to expand in your lungs), and topical antiseptic. It easily crosses the blood-brain barrier where it inhibits activity of acetylcholinesterase, which destroys acetylcholine, an information transfer molecule, resulting in better memory. It may counteract THC's activity, which leads to low acetylcholine levels."* Largely due to the presence of pinene, rosemary and sage are both considered “memory plants.â€"* Concoctions made from their leaves have been used for thousands of years in traditional medicine to retain and restore memory.
-Pulegone-"*mint, camphor, rosemary, candy."* It is implicated in liver damage in very high dosages. It is found in tiny quantities in marijuana."* Pulegone is an acetylcholinesterase inhibitor. That is, it stops the action of the protein that destroys acetylcholine, which is used by the brain to store memories."*
-Sabinene –"*Found in oak trees, tea tree oil, black pepper and is a major constituent of carrot seed oil."*"*
-Terpineol-"*floral, lilac, citrus, apple/orange blossoms, lime. "*It is a minor constituent of many plant essential oils. It is used in perfumes and soaps for fragrance."* It reduces physical motility 45% in lab rat tests… Couch-lock effect? "*
So in a nutshell, your plants produce terpenes as a byproduct of their resin glands (in this case; the trichomes.) Terpene production is a defense capability of your plant which helps ward off predators (some herbivores,) and can also be produced in response to physical stress that may be caused by living or nonliving things (humans, heat, light, environment, etc.) These are the primary source of the smell of your plants and there are many variables that can affect their production, physical and chemical qualities, and preservation.
Here is a more detailed example of how marijuana terpenes are measured in a laboratory environment.
http://www.srigc.com/Terpene Method.pdf
Chapter 2: So how do I help with the smell?
Carbon Filters
What is activated carbon? Activated carbon is charcoal that's been treated with oxygen to open up millions of pores between the carbon atoms. This process occurs at a very high temperature (around 1800 degrees Fahrenheit of steamed heat.)
Carbon filtering is a method of filtering that uses a bed of activated carbon (charcoal) to remove contaminants and impurities using chemical absorption. Activated carbon is very effective at removing the VOC's (Volatile Organic Compounds) produced by your plants. For intents and purposes, this guide will focus on air filtering.
Basically, each particle or granule of activated carbon provides a surface area full of pores for impurities to be exposed to. As the impurities passes through the carbon, they get absorbed (trapped) in the porous holes through chemical attraction. The more surface areas exposed, the better chance of filtration (which is why you want your carbon to be crushed to expose more surface area) because the larger surface area exposes more bonding sites. Particle sizes that can be removed by carbon filters range from .5 to 50 micrometers. As time goes on; the bonding sites on the carbon begin to fill up and the effectiveness of the odor reduction decreases. Once all the bonding sites on the activated carbon are full; the filtration ceases to be effective (and the carbon needs to be replaced.)
Here's a fun factoid; 1 pound of activated carbon contains the surface area of over 100 acres!
The efficiency of a carbon filter depends on several things:
- Airflow CFM (Cubic Feet per Minute.) The fan attached to your carbon filter must be of the appropriate CFM value to be as effective as possible.
- Molecule size of organic impurities (larger molecules are absorbed better than smaller molecules.)
- The pore size and distribution of the activated carbon (varies by method and manufacturer.)
- Temperature (lower ambient temperatures tend to absorb smells better than higher ones.) The reason for this is at higher temperatures, the VOC molecules start breaking down into smaller molecules. Activated carbon absorbs larger molecules easier than smaller, so we want to keep them in the largest state we can.
The Carbon Scrubber
The most common type of air filtering for growing is probably the carbon scrubber. These usually come in a 4" or 6" duct fitting variety, capped on one end with the duct fitting on the other end. These are usually cylindrical in shape; with the middle (core) being open air and the outer core being filled with activated carbon with pores all over the metal work of the outside and inside ring.
A fan is fitted either to the carbon scrubber itself or somewhere inline the ductwork leading from the scrubber. The fan must be appropriately rated to the CFM requirement of the scrubber, NOT the area of the grow room (if it happens to work out that it does both; pat yourself on the back.) The reason for this is that you need adequate air flow for the air to pass through the filter. The longer the contaminants are exposed to the filter media; the better the absorption.
That being said; you have to consider a few things here:
You need a fan with enough CFM to adequately suck air through the filter. Imagine the carbon chunks not being in there for a second and the fan running. Not a lot of resistance to sucking in the air, right? Now, fill that same void with crushed carbon, and suddenly the fan is working harder (which produces more heat as a byproduct) and working at a diminished rate.
I personally use a LEDWholesalers 6" Carbon Scrubber (rated for 470 CFM) with a Hydrofarms 400 CFM fan and it works quite well in my tent (4 foot by 4 foot by 7 foot.) If there's not enough CFM; you are not going to be sucking much air through the filter; decreasing the effectiveness of the scrubber. If you have too high of a CFM rating, you will be pushing air through so fast that it's not having time to allow those molecules of the impurities to cling on to the carbon.
You should always have your fan sucking air through the filter; not blowing air through it. I'll explain why:
The inline fan draws air into the chamber of the carbon scrubber by blowing air out of it. Drawing air in is better than blowing air in because it doesn't produce as much turbulence inside, which in turns allows for greater control of the airflow through your ductwork. Why should you care about turbulence? The airflow created by the fan on the scrubber is already fairly turbulent due to how the fan blades are in motion and by design of the fan blades. Turbulence is the swirling of air (as in vortices.) Vortices occur on the length of the fan blade and at the blade tip as the blade moves through the air. As the speed increases on the fan, there is more turbulence created and the sound levels increase as the vortices increase.
Blowing air causes more turbulence than sucking air does, and depending on where your fan is in relation to the scrubber; that turbulence can greatly diminish the CFM capability of the fan.
Sucking air through the filter also offers more advantages. By sucking air through the filter, you are creating a negative air pressure space inside the carbon scrubber. Negative air pressure is good because it keeps those odor molecules from escaping the scrubber once they are in there. The extra benefit is, depending on the size of your grow tent/space; you can possibly achieve negative air pressure inside the growing space; which on a tent would cause the inside walls to suck in slightly. This is a good thing. This means you are sucking more air through your scrubber than you are actually pushing (from your inline intake fans) into the tent. This causes not only those odor molecules to more effectively stay trapped inside your tent (as in, less likely to leak out through zipper holes, pin holes, passive air intakes, etc, but also gives the scrubber more time to suck them up for filtration.
On top of all that; most scrubbers come with a pre-filter on them. This is usually a white fabric loop that slips over the exterior of the scrubber. This should ALWAYS be on your carbon scrubber. It filters out larger micron particles (like dirt and dust) and keeps them from coating your activated carbon. Remember, carbon works at a diminished rate when it gets covered as there are less and less bonding points for the chemical absorption to happen. The pre filter makes sure the big stuff that doesn't need to get filtered stays out and only lets the smaller, smelly molecules through. If you were to push air through the filter; you are effectively coating the insides of the carbon with EVERYTHING that's in the air (and blasting the excess to your pre filter inside out.) Most pre-filters are machine washable (or wash by hand), and tumble dry on low heat in the dryer.
That's not to say you can't push air through a carbon filter and have it not work. I know for a fact there are several growers on here that use that same and very setup. What should be noted though; sucking air through does in fact provide the most efficiency for the scrubber and is also backed up scientifically (if that sort of thing floats your boat.)
Can I clean and reuse my carbon?
I've been reading a lot about this lately and the short answer is “sort of but the time invested versus just buying some new activated carbon isn't worth it†and the long answer is more of what you'll read below.
The Organic Materials Review Institute (OMRI) has produced a paper on Activated Carbon processing which includes the following:
"Carbon can be reused if the adsorbed substances are removed. This process is known as 'regeneration.' Simply heating the spent carbon at a given temperature for an adequate length of time can regenerate activated carbon to the point where it can be reused for tertiary wastewater treatment (thermal regeneration) (Mine Safety Appliance Corp., 1970). Thermal regeneration inevitably results in the loss of carbon (Battelle, 1970). Also, thermal methods may not be the most efficient, inexpensive, or reliable method, so a number of solvents, acids, and alkalis may be employed to remove the adsorbed substances. These include such things as carbon tetrachloride, hydrochloric acid, hydrogen peroxide, potassium hydroxide, sodium hydroxide (Mine Safety Research Corp., 1970). Optimization of the regeneration process depends on the substances adsorbed as well as the structure of the activated carbon."
The problem with carbon regeneration is the removal of those volatile organic compounds once they've bonded with the carbon. The fastest way is through high temperature steaming (around 1800 degrees Fahrenheit from what I gather; although I've read some reports that say around 800 degrees may burn them off.)
The other methods involve using chemicals to break down the molecules before applying heat (which may attribute to needing a lower heat level if they've been chemically washed.)
Testing the efficiency of regenerated carbon is also very difficult. You can google a lot of web sites of growers that say "oh yeah I totally baked and reused my carbon" and maybe there's some merit to it; but I prefer to err on the side of science and it just seems to be out of the reach of most conventional people.
At this point though; unless you want to mess with chemicals on something that costs a few bucks online or at the pet store; or unless you own a furnace or heating device that can produce that much heat, it's really not worth it. In my humble opinion; if you want to try to extend the life of your carbon; take a hammer to it. Smash it in more pieces; which will expose more surface area and bonding sites. Otherwise; pony up the dough; because the time spent on doing a "home brewed" regeneration could have been time spent on making the money to get brand new manufactured carbon. Just my two cents though; take that last bit with a grain of salt if you are feeling like trying something new
Essential Oils
This was taken from the US Library of Medicine National Institutes of Health:
"Recent studies of olfactory blocking have revealed that binary odorant mixtures are not always processed as though they give rise to mixture-unique configural properties. When animals are conditioned to one odorant (A) and then conditioned to a mixture of that odorant with a second (X), the ability to learn or express the association of X with reinforcement appears to be reduced relative to animals that were not preconditioned to A. A recent model of odor-based response patterns in the insect antennal lobe predicts that the strength of the blocking effect will be related to the perceptual similarity between the two odorants, i.e. greater similarity should increase the blocking effect. Here, we test that model in the honeybee Apis mellifera by first establishing a generalization matrix for three odorants and then testing for blocking between all possible combinations of them. We confirm earlier findings demonstrating the occurrence of the blocking effect in olfactory learning of compound stimuli. We show that the occurrence and the strength of the blocking effect depend on the odorants used in the experiment. In addition, we find very good agreement between our results and the model, and less agreement between our results and an alternative model recently proposed to explain the effect."
What are essential oils?
Essential oils are liquids extracted from plant matter by methods of pressing, solvent extraction, or steam distillation. The liquids are naturally occurring organic oils that come from things like seeds, leaves, and flowers to name a few. The oils are then redistilled or refined down to reduce unwanted materials in the final product.
Essential oils are made up of (wait for it...!) terpenes, esters (like ethyl acetate, the most common ester found in wines,) aldehydes (formaldehyde is an aldehyde,) ketones (fructose and acetone are examples of ketones,) phenols (like carbolic acid, a smelly phenol used for mild antiseptics,) oxides, and alcohols.
These oils also contain trace elements, which give the oils its character and enhance the ability to blend with other oils. These trace elements give the oils the unique characteristic ability of odor neutralization. When multiple trace elements are combined they work in synergy with each other which improves the effectiveness and range of application.
How do essential oils work?
Essential oils evaporate easily, infusing the air without leaving residue behind (highly volatile.) They do not react with odor causing chemicals/particles to remove them from the air. This means that unlike a carbon scrubber, they do not trap molecules and confine them. This also means they will do nothing for filtering out possibly hazardous chemicals/molecules (hopefully you are not working with anything that causes those in the first place.)
Essential oils are different than deodorizers (which just mask the smell.) Essential oils behave similar to a solvent. For example, picture the odor causing molecules as a solute (a component of a solution that is dissolved in the solvent.) The essential oils are diffused into the air through a method that optimizes absorption (process by which a fluid is dissolved by a liquid or a solid) and adsorption (process in which atoms, ions or molecules from a substance (it could be gas, liquid, or dissolved solid) adhere to a surface of the adsorbent.) If you get the two mixed up; that makes two of us. J
Things that affect absorption/adsorption:
- Surface area
- Contact time
- Particle size
- Temperature
- Concentration of both materials (oils and odor causing compounds)
The essential oils physically combine with the odorous material to form a new physical compound. The new combination should have no odor. That would be great if all conditions were 100% ideal, but certain odor molecules are heavier than others and are harder to neutralize (specifically in this case, hydrocarbons.) Many terpenes are hydrocarbons, but oxygen-containing compounds such as alcohols, aldehydes or ketones (terpenoids) are also found. That's not to say it won't neutralize the odors; just that those hydrocarbons have bigger boxing gloves on when it comes to combatting the odor molecules. The ultimate goal of the essential oil is to trick the human olfactory system (your sniffer) into not smelling something that is there. Success is based on not sensing any unpleasant odor in the air.
There are some things to keep in mind about essential oils. Not all essential oils are created equally. There are a very limited numbers of these oils effective for the process of odor neutralization. The effectiveness depends on how well the oils are chosen and blended to effect the correct chemical or physical reaction with odorous compounds. In short, this means you don't want to just start infusing just any essential oils into the air to try to combat marijuana odors. There are many essential oils that serve mostly as fragrances and used in perfume scents.
What's an example of an essential oil product?
ONA Gel
I'm sure if you spend any amount of time in searching for odor control methods for marijuana, you've probably stumbled across a product called ONA (Odor Neutralizing Agent.) ONA is a liquid based mixture of essential oils. It's non-toxic and environmentally safe. It's safe for your babies, it's safe for your doggies, it's safe for you. It's a green product. That said, that doesn't mean you should go sticking your nose into a jar of concentrated soaked ONA gel. That doesn't mean you should grab blobs of gel and roll it around in your hands. That doesn't mean you should eat the stuff or put it in an area kids or pets can eat. You shouldn't do that with almost ANY essential oils. You can find the MSDS (Material Safety Data Sheets) on their product website (MSDS sheets are excellent sources of information for products of this nature; I use them all the time in my work.)
I'm picking this particular product for it's essential oil use and because I've personally used it on a few grows with a great deal of success. If you do a quick search on AFN however; you'll see others were not as lucky. I've also read quite a bit of misinformation on here about this product; so I hope to clear up a few things about it (and no I'm not a spokesperson or work for them; I'm just a guy who tries stuff and if it works, spreads the word.) I've been wondering how some people have not had success with it while myself (and others) seem to love it.
Here are some product flaws of both right out of the box (see? I'm not totally biased here :smoke: ) Essential oils are most effective with a method of dispersion to allow them to mix with the odorous compounds. Neither the ONA block or the ONA gel quart jars have a method of dispersion other than open air, which relies on natural air movement or fans of some kind. The containers must also be placed in an area size appropriate to the container. If you place a quart jar in your living room and expect amazing results, you're going to be sorely disappointed. I use these in the bathroom (on top of the john) and next to litter boxes. Even without dispersion; they are close enough in proximity to react with the odorous compounds produced by the litter box and my *ahem* toilet.
I've used ONA quart jars in a 3 foot by 2 foot by 5 foot grow tent and had amazing results with a small 6†clip on fan blowing on the open mouth of the jar. No smell on the outside; curiously fresh smell of “linen†scent on the inside. I've used ONA quart jars on a 4 foot by 4 foot by 7 foot tent with a massive amount of autoflowers inside (again with a fan blowing on it for dispersion.) It helped with the smell immensely (but ultimately used the combination of a carbon scrubber and the ONA to kick the smells butt.) Hopefully that gives you an idea of what kind of limitations that particular design has based on volume. There are larger volumes of ONA product that you can buy (for more commercial applications), but considering the limitations of essential oils (they bond with the odorous compounds, not destroy them,) your needs and mileage may vary.
To address the people that claim it flat out didn't work; I think there are multiple possibilities of why not. Did they take measures to properly disperse the ONA? Is the ONA right next to a powerful exhaust fan that's pulling those same odor absorbing molecules right into the exhaust/scrubber? Is the ONA product of the right size for the dimensions of the grow room? And most important to point out is that essential oils (not ONA specifically) can only bond with certain carbons and hydrocarbons. Every marijuana plant out there produces different types of terpenes/terpenoids at different quantities. It's entirely possible (and feasible) that the essential oils in ONA may indeed NOT be bonding with the terpenes being produced by your plant!
There! I said it! ONA may in fact not work for your plants not based solely on the product design of mixture of essential oils, but in fact by the genetic design of your plant! Consider that a limitation of essential oils (they are not universally great at bonding with anything and everything.)
That said, I would still recommend at least trying it out as a supplement to your odor control. If one technique proves to be very useful; surely other proven techniques combined will prove to be of even more use.
COMING SOON!
Deodorizers
Ionizers
I want to say thank you for the read if you managed to get this far! I plan on updating the guide with a more in depth look at deodorizers and ionizers that are used in growing, as well as updating the guide with some pictures for more visual stimulus!
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