Indoor Smell even with carbon filter

[londonpeach]

Hello lovely people!

1st things 1st - I love this forum and think you're all an absolute bunch of sweeties and the breadth of knowledge and help available amazes me. Thank you for making this such an amazing place :Gold:

On to the issue:
I have a 60x60x140 tent with 2 plants in flowering.
My odor control kit consists of a set I bought together from an online hydroponics store - a Buddy 350 m3/h (206 cfm) filter and a fan which is listed as 'up to' 187 m3/h (110 cfm). These are mounted in the tent, with 2 short pieces of ducting with 2 bends - maybe 1m overall length. Inside the tent, apart from plants, is also GN Ms0006 and an oscillating fan.
I vent into the same room, unfortunately this is my only option, but always strive to keep fresh air moving through the window. I haven't had plant problems w/ regards to airflow.

My problem is - there has been an increasing amount of smell creeping through lately! It started in late veg and been getting progressively worse. I tried tweaking with the fan's cfm to slow it down but slower just makes it smell more so I'm going at 100% now. Air fresheners do not help.

To reduce the number of possible issues:
- The ducting is securely strapped to fan/filter by silver tape with no gaps and there are no air leaks around anywhere
- the smell is definitely coming from the duct as I can smell it when I direct it at my face
- there is slight negative pressure in the tent, not much but some
- I haven't had humidity issues in veg that would affect the filter's performance
- I am running a passive intake

Do you guys think this is an issue with the filter or (what I suspect) is my fan not powerful enough to get rid of the smell? I realize that with the ducting bends and carbon filter the fan might be running at a reduced cfm, then again from what I read the fan SHOULD be running at less cfm than the filter. Is the gap between my cfms too big?
Or is the Buddy brand just not good enough and should I get a proper one like Rhino? (I appreciate that a better filter will ALWAYS help but if the issue is the fan then no point paying twice)

The fan has been sold to me as an appropriate one for airflow control since it's such a small space - is this the reason I am having those issues?

Any help is much appreciated, take care and have a great day
:tiphat:

 

[namvet25]

If you have sufficient air flow running through your filter and your still getting smell,more than likely your filter is not very good.

 

[Heavily Medicated]

I've noticed that the warmer the temps the worse the odor. It seems to really make a difference if you can keep your tent in the 70's, once into the 80's, I can notice an increased odor. Just my experience.

 

[londonpeach]

Thank you for the replies.

If you have sufficient air flow running through your filter and your still getting smell,more than likely your filter is not very good.

That might be the case, but what do you define as sufficient airflow? With the setup I described above would you say the fan I have as it's running at the moment is sufficient? (as in - plants are not complaining, but what do I know maybe I need more airflow?)

I've noticed that the warmer the temps the worse the odor. It seems to really make a difference if you can keep your tent in the 70's, once into the 80's, I can notice an increased odor. Just my experience.

Hello there Thanks for the tip but my temps are nice and cool now so definitely not that :<

 

[Twigglius]

Honestly it sounds like you have everything set up just right, the only thing I can think is that charcoal quality in your filter is bad. I had that issue with a random brand filter I bought.

If smell is a huge issue where you are, I'd buy a Phresh filter and see if that helps. Since I bought my Phresh brand filter, after having very similar issues, I haven't thought twice about going back , it's a champ.

For your reference I run a 190cfm fan in a 3'x3' tent with a 200cfm Phresh filter and it works like a charm. I'm kinda close to blowing out the CFM rating in the filter, but like you I vent into the same room the tent is in and I have several bends in the ducting that bring the overall CFM down a bit.

best of luck!!

 

[Son of Hobbes]

Hello lovely people!

1st things 1st - I love this forum and think you're all an absolute bunch of sweeties and the breadth of knowledge and help available amazes me. Thank you for making this such an amazing place :Gold:

On to the issue:
I have a 60x60x140 tent with 2 plants in flowering.
My odor control kit consists of a set I bought together from an online hydroponics store - a Buddy 350 m3/h (206 cfm) filter and a fan which is listed as 'up to' 187 m3/h (110 cfm). These are mounted in the tent, with 2 short pieces of ducting with 2 bends - maybe 1m overall length. Inside the tent, apart from plants, is also GN Ms0006 and an oscillating fan.
I vent into the same room, unfortunately this is my only option, but always strive to keep fresh air moving through the window. I haven't had plant problems w/ regards to airflow.

My problem is - there has been an increasing amount of smell creeping through lately! It started in late veg and been getting progressively worse. I tried tweaking with the fan's cfm to slow it down but slower just makes it smell more so I'm going at 100% now. Air fresheners do not help.

To reduce the number of possible issues:
- The ducting is securely strapped to fan/filter by silver tape with no gaps and there are no air leaks around anywhere
- the smell is definitely coming from the duct as I can smell it when I direct it at my face
- there is slight negative pressure in the tent, not much but some
- I haven't had humidity issues in veg that would affect the filter's performance
- I am running a passive intake

Do you guys think this is an issue with the filter or (what I suspect) is my fan not powerful enough to get rid of the smell? I realize that with the ducting bends and carbon filter the fan might be running at a reduced cfm, then again from what I read the fan SHOULD be running at less cfm than the filter. Is the gap between my cfms too big?
Or is the Buddy brand just not good enough and should I get a proper one like Rhino? (I appreciate that a better filter will ALWAYS help but if the issue is the fan then no point paying twice)

The fan has been sold to me as an appropriate one for airflow control since it's such a small space - is this the reason I am having those issues?

Any help is much appreciated, take care and have a great day
:tiphat:

Hey brother I've noticed a few things about your setup that don't seem quite right to me:

Buddy 350 m3/h (206 cfm) filter and a fan which is listed as 'up to' 187 m3/h (110 cfm). These are mounted in the tent, with 2 short pieces of ducting with 2 bends - maybe 1m overall length. Inside the tent, apart from plants, is also GN Ms0006 and an oscillating fan.

For starters, your fan is not appropriately sized to the filter. The "350 m3/h (206 cfm)" rating is the optimal rating of CFM required to be as efficient as possible as set by the manufacturer. They vary greatly between manufacturer and carbon filter design (my 6" carbon scrubber is rated for 470 cfm.) If anything, you would want to be very slightly OVER that rating, as to take into account the CFM reduction from attaching the scrubber (which I would say you could guesstimate around 10% loss at least.) You're easily running at 50% of the required CFM, and without the proper amount of contact time with the activated carbon, the scrubber becomes inefficient and doesn't do its job.

I tried tweaking with the fan's cfm to slow it down but slower just makes it smell more so I'm going at 100% now.

I think that validates my "under-powered" point right there.

Are you using your pre-filter on the scrubber? That's the white fabric sleeve that fits over the scrubber. That's important to keep on (and keep cleaned after each grow) as that blocks out larger micron particles like dust and dirt. Those larger particles coat the activated carbon, which reduces the amount of bonding points for adsorption to occur (which is a bad thing.)

Sometimes you can take a hammer or a blunt object to the side of your scrubber (careful with how hard you swing though lol) and smack the sides a bit all the way around several times. The vibration and impact will help move and break up some of the carbon inside, exposing more surface area (which is a good thing.)

there is slight negative pressure in the tent, not much but some

Negative air pressure is an awesome thing with grow tents and carbon scrubbers. You WANT your tent walls sucking inward when running that scrubber. That means you have an intense amount of pressure at the point of the scrubber sucking air in; meaning those odor causing molecules are going to be far less likely to escape out of the passive air intake, holes in the seams of the tent, etc etc, and more likely to pass through the activated carbon.

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 adsorbed better than smaller molecules.)
• The pore size and distribution of the activated carbon (varies by method and manufacturer.)
• Temperature (lower ambient temperatures tend to adsorb smells better than higher ones.) The reason for this is at higher temperatures, the VOC molecules start breaking down into smaller molecules. Activated carbon adsorbs larger molecules easier than smaller, so we want to keep them in the largest state we can.

Air fresheners do not help.

Air fresheners are usually just odor maskers. You could try a product like ONA (I would get the gel and not the ONA blocks though it's an essential oils product and in my opinion works very well in SOME setups (it can be hit or miss with a lot of members and you'll find a lot of positive and negative feedback on here; I've got my own personal feelings about some of those but we'll try to stick with the facts here )

Check this out:

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.

One of the problems with essential oils is that there are over 120 different kinds of terpenes in cannabis and depending on the composition of the essential oils, they do not all bind as effectively as others (if at all.) That's another reason why some have great success with strains X in conditions Y and others do not with a "different but same" setup (in my opinion.)

Things that affect absorption/adsorption:

• Surface area
• Contact time
• Particle size
• Temperature
• Concentration of both materials (oils and odor causing compounds)

I've noticed that the warmer the temps the worse the odor. It seems to really make a difference if you can keep your tent in the 70's, once into the 80's, I can notice an increased odor. Just my experience.

Terpenes are 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.

Hope that helps out bro; if it were me in your shoes, I personally would look at beefing up that extraction fan. :Sharing One:

 

[strawberry]

I wouldn't go against what SoH says as I'm new to the game ;-)

However, I had odour control problems and eventually found, like Twigglius, the culprit to be a dodgy filter. Just my "My 2 cents"

Best of British to you London

 

[AndyBotwin]

One thing I haven't seen mentioned is that the higher the humidity, the less effective a carbon filter operates. Normally this isn't a big deal since we run higher humidity when the plants are in veg and not as smelly, and lower humidity during flower when they stink the most. My weather has been swinging all over the place lately, and I can definitely tell a difference in the smell from the output vent when the humidity gets well up over 50%. Yesterday and today the humidity in the tent is back down in the low 40s and I can't really smell anything outside the tent. I've found this to be even more noticeable when the carbon filter is older and has been used for many grows (like mine).

 

[Muddy]

I also think it's the quality of the filter. I've been running a 4" Phat for over 3 years and am only now starting to notice a bit of smell when the plants are in full flower. These filters are also more effective when the air is pull and not pushed through them.

 

[Villain]

Sounds similar to a problem I had on my last grow, agree with all about shite carbon filter, if you are from London I would also be careful of local grow shops, I bought my previous filter online from a respected store and had no problems, then bought same brand (rhino) and had problems from my LGS