Grow Mediums First Grow - Hydro/DWC Training SCROG w/ Bagseed Photos

Found this in another forum. Posting it here for reference...

Lucas Formula (ACTUAL)


To grow with the Lucas formula you use 8ml micro, 16ml bloom, GH Flora Series nutes. this should come in around 2.0 EC and works great for HPS light.. (or MH if you are oldschool and want lower yields)
for fluorescent light, I suggest you drop nutes strength to 5ml micro, 10ml bloom, per gallon of water, about EC 1.4 ( as a rule of thumb, I would try not to exceed 1000ppm @.7 conversion when using fluoro light )
I veg with bloom nutes if veg happens under HID
alternatively, you can grow with GH Flora Nova Bloom, a one part nute.. and you could veg with their Veg formula, which will produce a LOT of veg growth.. taller plants, larger (hollow) stems...
for a 600w light, in hydro, I would use a rule of thumb of 1.5 gallons of reservoir or root zone medium per 50 watts of light..

that means 18 gallons for a 600w lamp..
that could be 18 1 gallon pots of hand watered medium, or ONE 18 gallon pot per 600 watt lamp.
Consider a Hydro Hut with a Multiflow system.. the Hydro Hut will provide light proofing, the frame of the hut will support your light and fans, and the Multiflow will provide an ebb flow system with pots large enough (2 gallons), to support large plants, I suggest 9 buckets per 600w.. in a 3x3 hydro hut...
as to your question about what size to grow the plants to.. I suggest you veg to a height of 18"-24" before blooming... cut off the top 4", and remove the bottom 3 branch pairs 2 weeks before blooming.. Expect the plants to grow an additional 2-3 feet taller after you begin 12/12 lighting..
in terms of multiple lights, for each 600w, provide a 3x3' footprint, regardless of whether you fill it with one plant or nine.
btw, the reason the tomato outside grew smaller than indoors, was partly because it got less hours of light per day..
I have great respect for people who grow in handwatered pots.. my bias is to hydro because of the automatic irrigation.. allowing for unattended gardening for a week at a time..
I also like to use a standardized nutes program, instead of trying to teach people how to "feel" what the plant needs. Many beginning gardeners chase perceived nutrient defficiencies with additives that create more nutrient problems...
plants grow well despite all the things we do to try and force them to grow bigger faster and stronger.. focus on good light, good air, good temps, good irrigation and oxygen delivery, and good feeding strategies.. iow, focus on everything <g>, then try to do less and let the plants grow.

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The current Lucasized Formula with GH Flora is still 0-8-16 as you said. Other nutes, such as PBP can also be made to approximate similar NPKMg values, for example PBPBloom @ 15ml/gal plus 5ml/gal Cal Mag.., or 8ml/gal Flora Nova Bloom

Both with target TDS @.7 of about 1300ppm (use less FNB, like 6ml/gal if your TDS exceeds 1400 with 8ml)

The original reservoir strategy I learned from pH was to dump and replace as you described, once an equal volume of addback water has reached. IOW, when a 20 gallon res, got 20 gallons of top up water, the res was dumped and refilled at fresh 0-8-16. This was not with pH adjusted water, because it works best to allow the res pH to fluctuate within a range of 5.3 to 6.3

An alternate reservoir management strategy I now prefer, is to add nutes to the reservoir in the addback water. The goal is to bring the reservoir back up to 1300ppm. In this strategy, I feel a single res change at harvest is sufficient.

Despite the obvious concern that this non dumping approach allows toxins to build up, I never experienced toxin buildup. this surprised me and caused me to alter my thinking about plant metabolism. It seems they do not excrete toxins the way organisms with digestive tracts do.

How much nutes goes in the addback water varies by res to light ratio. For example, a 50 gallon res under a single 1k can be topped with 33% of 0-8-16, and the 1300 tds will be approximately achieved... Im not a stickler for that number, and am happy fluctuating anywhere between 1100 and 1500ppm over the course of a week, such that if one chooses to top only with water for a few days, the nuteing can be done in a single session each week.

If the same 50 gallon res is used under twice as much light, it will probably require twice as much nutes in the addback water.

The most primary concern is to achieve the TDS increase, while staying within pH range

adding nutes lowers pH, so sometimes one can avoid pH adjusting, by adding more or less nutes
adding water raises pH, so dont adjust a reservoir, until it is topped up with water and nutes
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> to grow with the Lucas formula you use 8ml micro, 16ml bloom, GH Flora Series nutes... [does that mean you mix veg and flower ferts together in the res...? and if so, why...?]
veg and flower is not applicable here.. Flora series nutes is a 3 part system, of which the micro is the source of N, and the bloom is the source of P and K.. mixing them as above, 0-8-16 is a bloom mix due to the low N and higher P and K.. I omit the Grow nute, which increases N.. because that is how the formula is biased.. its a bloom formula.. all about everything that happens up to harvest so it wont have too much N at the end
>this should come in around 2.0 EC... [i do not understand EC... i am assuming that the ONLY way to know the amount of nute's you have in the res is by measuring them AS THEY GO IN and that there is no meter a person can use to check nute levels... but what is EC please...]
to grow hydro, I like owning the Hanna HI98129 http://tinyurl.com/33cths
it allows me to measure TDS both in .5 and .7 conversions, as well as EC
EC is Electrical Conductivity
the way to work with a meter, in hydro, is to take readings of the EC or TDS, adding nutes periodically with the top up water, to maintain the target nute EC or TDS..
the target EC or TDS is the same value produced when you mixed a res with the measured nutes
>I veg with bloom nutes if veg happens under HID... [is this a reference to the mixture of 8ml micro, 16ml bloom mentioned earlier...?]
yes 0-8-16 is bloom nutes
> alternatively, you can grow with GH Flora Nova Bloom, a one part nute.. and you could veg with their Veg formula, which will produce a LOT of veg growth.. taller plants, larger (hollow) stems... [is this really so different from the fert mixtures mentioned above...? i do want vigorous growth for max yield...]
yes it is REALLY different to use veg nutes during veg
most hydro grows dont invest a lot of time in vegging, and it is impractical to dump a res that was used for such short periods
ideally though, if you have a veg area with veg nutes, and a separate bloom area with bloom nutes, you would be rocking..
example, veg area with Flora Nova Grow at EC 2.0, which is TDS 1000@.5 conversion, under a 600w HPS
then a bloom area also with 600w HPS, but with Flora Nova Bloom @ EC 2.0 (about 6ml/gal)
> -for a 600w light, in hydro, I would use a rule of thumb of 1.5 gallons of reservoir or root zone medium per 50 watts of light.. that means 18 gallons for a 600w lamp...[what would you recommend for 1000 w lamps...?]
30 gallons..
which is why Im pointing you to the Multiflow, it has a 50 gallon res, and can be had with all the hoses and kit you need, including 5 gallon buckets as an option. for 6000 watts you would want about 180 gallons of water.. you could get by with 3 50gallon barrels feeding the buckets..
one caution on the way..
if you re-use your growrox, you need to get all the dead root bits out of them, quite a chore.. otherwise you may have a problem with insects feeding on the roots, for example the larvae of fungus gnats..
so, if you can make 2.5 gallon pots work, you will have half as much work on the cleaning, or disposal and replacement, of rox each cycle..

> would the different formula in the veg room give you a better plant to put into the flower room...? better stalk development, root growth, etc.
yes, and more yield..
here is another iteration for you to consider
once you are ready to veg, and lets say that you want to use the bloom room for vegging..set the lights to 18 hours per day.
mix nutes intended for veg, but on all the addbacks, use bloom nutes
example, 600w light, 25 gallon res, at 6ml/gal Flora Nova Grow, topped with Flora Nova Bloom for the remaining veg time plus the bloom time as well.. how much in the addback, about 2ml per gallon.. confirmed by a TDS of about 12-1400 @.7 conversion (about 2.0 EC)
a TDS or EC meter wont tell you how much Nitrogen is in the nutes mix, we are only measuring the overall conductivity of all the stuff in the nutes, combined, not segregated by ingredient.. so, changing from Grow to Bloom nutes, even when keeping the same TDS target, does not produce the same growth style or rate..
with bloom nutes plants have woody stems, and yellower leaves
with veg nutes plants are brighter green stretch more, and get hollow stems
smoking greener material is less pleasant than smoking less green material..
however, setting up a plant with high nitrogen at the beginning, and low N at the end, has the potential to produce bigger buds.. better harvests
its not that the plants grow "faster" its that they grow "fatter"

> You seem to speak highly of Flora Nova Grow @ 1400ppm during veg, but the local hydro shop doesn't carry Flora Nova. What's the equivalent recipe made out of the 3 part Flora?
The equivalent recipe to Flora Nova Grow at 8ml/gal is to use the General Hydroponics standar veg formula for the Flora series.. 15ml/gallon of Grow, 10ml/gallon of Micro, and 5 ml/gal of Bloom
The Lucas formula, 0-8-16 is very close to the standard GH Flora bloom recipe of 5-10-15 g-m-b.. you can use either recipe if you already own Flora Grow.... the GH 3 part bloom formula is a bit higher in Nitrogen than the Lucas formula..
nitrogen is good for vigorous growth.. its only bad in high quantities before harvest.. but by high quantities, I mean double what any of the above bloom recipes provides.. so, no need to worry about too much N with GH bloom formula..

> so what this is saying is to keep the N levels higher as in the veg mode while entering into the bloom cycle for the first week at least, letting it taper by adding bloom to the add back...?
yes
> and that this may give a healthy kick in the pants to the cola development...?
yes
the tradeoff is the leaves are greener, which is not good when it comes time to smoke..
> has anyone done any follow up on this yet...?
I give credit to Mr. Highway for writing an article in which he used the term, "feeding the stretch". As I understood it, he wanted to make the high growth rate of the first 2 weeks of 12/12, to have plentiful nitrogen
> has this become the/a standard method...?
nope.. everybody does what they do.. then some of us tell others, then some of us read how others do it, and some of us try to sort out whose advice to follow..

>>>

Flora Nova Bloom has the same elemental values as the 0-8-16 Flora Series recipe.
I think 800ppm @.7 conversion of 3 part Flora is fine under fluoros, but When going to HID light, I have no problem going right to 13-1400ppm @.7 conversion.. I dont bother to increment up to that value, but if it makes you feel better, you can.
On a .5 conversion meter the eqivalent HID light target ppm is 1000, the Fluoro light target is 600ppm
I agree with gisisi who said
"whatever ppm it reads at 0-8-16 in 1 gallon of water
is what you shoot for.
Same for 0-5-10 when you are using low intensity flouroscents, such as T12s."

> I am using your formula at 3/4 strength of the 0-5-10 as the light is only a 250hps and they don't like too many nutes.
that is not correct usage of the formula.. For a 250HPS you should use 0-8-16... I NEVER alter the recipe to use 3/4 strength..
the formula you are using is too low in Mg, which is the central element in the chlorophyl molecule. You NEED the Mg in the full strength formula.
as to your curled leaves.. I would look at increasing the amount of dissolved oxygen in the root zone.. As a rule of thumb, if you have 10 gallons of DWC root zone, you should be adding bubbles from at least a 5watt airpump.. but if you have temps above 72 in the water, the plants will be much happier with 1 watt of airpump per gallon of water
iow, for warm water I recommend a 10 watt airpump for a 10 gallon root zone..
and lastly, your plants look absolutely beautiful, congratulations.. the only other thing I think could help, is better ventilation of the canopy.. it looks dense enough that in some spots it may be difficult for air to move thru the mass of leaves and colas..
If air does not reach part of the canopy, CO2 will be lacking to those areas, and growth will be stunted..
in conclusion 3 suggestions
1. 0-8-16, not diluted 0-5-10
2. LOTS of bubbles
3. plenty of airflow
btw, you dont mention your water and canopy temperatures.. they should be below 70 for the water, and below 80 for the canopy

> can someone tell me the lucas formula for floranova grow and bloom?
Try 6ml/gallon and see if it gives you EC 2.0, which is what you want. Flora Nova varies in thickness, so you should use EC to confirm your nutes dosage.
An EC of 2.0 is the same as a TDS of 1400 on a meter that uses .7 conversion.
An EC of 2.0 is the same as a TDS of 1000 on a meter that uses .5 conversion.
Some EC meters read 4 digits, in which case EC 2.0 is the same as EC 2000
> Q: Nutrient question. When I use 0/8/16 my ppm = 1490. I have read that we can reduce, but do we just reduce both, or better to reduce the micro or grow.

keep the amount of micro and bloom in the same proportion, but use less or add more water (if you are currently mixing based on a certain amount per gallon, lower the amount per gallon, or raise the number of gallons in the calculation. 1490 is a little too high
>Enough is enough, read for yourself!
There have been several questions lately on how to alter the Lucas Formula by adding Calcium, or Nectar, or Liquid Karma, or even using the formula backwards for veg at 16micro/8Bloom without Grow.

I do not recommend any of those changes, but if you want to get into designing your own nutrient formula, I suggest you learn to use the spreadsheet.

The Lucas formula is 8micro/16bloom. If someone tells you it needs an additive, dont ask me how to use it, cause I dont.

also, measurements are in milliliters, not "parts" cause nobody knows how many mil are in your "part". And most certainly, 1 part is NOT 10ml, nor 5ml, nor any other value. "Part" has no measurable meaningful value.

If you want a veg formula, I suggest the original GH recipe, that uses the Grow@15ml/Micro@10ml/Bloom@5ml This is the same as what is inside the Flora Nova Grow bottle.

For a bloom formula that is the same as the Lucas Formula but uses only 1 bottle, I recommend Flora Nova Bloom.

The Flora Nova products are a bit thick, and depending on how you shake the bottle, or how little you pour out, it varies in strength slightly. I suggest you start with 5ml/gallon. Then verify if you have achieved TDS between 13-1400 on a .7 conversion. Thats 2000EC or TDS 1000 if your meter is a .5 conversion.

Please understand the Lucas formula is very very simple, and does not need anything added to it, other than to adjust pH to 5.8 for hydro.

If you come here asking how to modify the formula, or reporting that someone told you to add things to it, feel free to do that and let us know how it works out for you, but please dont expect me to keep telling you over and over, that I do NOT RECOMMEND ADDITIVES!

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Lucas Formula (THIS IS A MODIFIED VERSION FROM SOMEONE ELSE. I'll keep this for the other info in it.)
General Hydroponics Flora Series Feeding Strategy - Lucas Formula

G-M-B (Grow-Micro-Bloom)
0-5-10 - For Vegetative cycle (18/6)
0-8-16 - For Flowering cycle (12/12)

The numbers above indicate the number of milliliters (ml) of Flora Grow, Micro or Bloom formulas that I use in one gallon (US Liquid) of nutrients.

You will notice I dont use any of the Flora �Grow� formula, do not need to, the Flora "Micro" provides plenty of Nitrogen.

There are two ways to work with this formula:

1. Top off the reservoir daily using a pH corrected water solution as required to maintain full reservoir level. After adding back an amount of water equal to the amount of your reservoir capacity you should change the reservoir and put in fresh solution.

2. Top off the reservoir daily using a pH corrected 100% strength nutrient solution as required to maintain full reservoir level. Continue to use this nutrient solution without dumping the tank unless the PPM rises above acceptable levels.

Between vegetative and flowering cycles you should dump your nutrients, then flush (possibly with Clearex) to remove salt buildups, then change to the other feeding program. Always shake your GH nutrient bottles before using them!

For young plants, just transplanted into the hydro setup, give them 50% strength nutrient mix to prevent overfeeding them while their young. Gradually bring up the mix to full strength as they grow over the next few weeks or so.

The lucas formula is normally intended for use with RO or near 0 PPM water.

NOTE: The Lucas formula eliminates the need for Epsom salts to correct (Magnesium) Mg deficiencies in most normal feeding programs recommended by manufacturers. Cannabis needs a lot of Magnesium to thrive.

The Flora Micro is providing the Nitrogen and the Magnesium in the proper balance, thus there is no need for the Grow formula and little or no room under the maximum acceptable ppm limit of 1600 @ 0.7 conversion.

Calculated EC/TDS levels:

EC microsiemen:
0-4-8: 946 �S
0-5-10: 1184 �S
0-8-16: 1894 �S

TDS @ 0.5 conversion:
0-4-8 = 473 ppm
0-5-10 = 592 ppm
0-8-16 = 947 ppm

TDS @ 0.7 conversion:
0-4-8 = 663 ppm
0-5-10 = 829 ppm
0-8-16 = 1326 ppm

Addback Calculator - (For Advanced Users)

Say you were running the 0-8-16 formula, at 0.7 conversion with a 22 gallon res. When you first fill it up, your ppm will be around 1330.

Now you have been growing for a week, and some of the water has been taken up by the plants, some has evaporated, and now your res is at 947 ppm. You need to get your ppm from 947 to 1330. Here is the equation:

((target - current) / target) * 8 ml per gallon * res gallons = Flora Micro (ml) double this figure to get Flora Bloom (ml)

Example:

((1330 - 947) / 1330) * 8 * 22
(383 / 1330) * 8 * 22
0.3 * 8 * 22 = 53 ml Flora Micro

53 ml Flora Micro, double that and you get 106 ml Flora Bloom. So 53 ml Flora Micro and 106 ml Flora Bloom to add back to your 22 gallon res to get you from 947 to 1330.

Using Hard Water GH Micro

I had been experimenting with using the Hard water Micro as a substitute for the normal Flora Micro, this to account for my hard 350 PPM water and the lack of a large enough RO filter at the time. It has worked well for me. I just kept my reservoir below 1150 PPM @ .5 conversion and its all good.

One tip - do not pH down this stuff, the hard water micro will drop pH gradually over the next 24 hours, for example I mix up a batch, it is at like 6.2, the next day, its at 5.6-5.8 after running in the system for a while. If I pH downed that to 5.7 before putting it in the system, it ended up as low as 4.8-5.2 by the next day.

My conclusion, the hard water micro was buffering the alkaline crud in my water, it just doesnot do it ASAP fast like the phosphoric acid.​
 
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BTW, I've added the link to #5 to the place I got the PVC parts. They've got some crazy stuff there and some nice manifolds useful for multi-bucket systems. I'd never seen a "slip slide T" before til now. That'll help folks with DWC bucket SCROGs make frames that are more easily raised.
 
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Hey TX Old Dude, Wow, you have been doing your homework bro! I have already learned so much reading through your grow journal!

Can't express enough gratitude to you, for how committed you are to doing things right. Planning, and asking questions all the time, as I do.:tiphat:

Man, am I ever subbed, and excited to watch your progress. I KNOW that you will be very successful with your new adventure.

I was looking into using a scRog for my 4 x 4 tent (in soil), for my first indoor Photo grow. I don't think my back or neck could handle the time it can take to train your plant/s to the screen.
Anyway when I was researching a couple of weeks ago on scROGing a came across some good info over at imag. In case you haven't read it here is a link.
https://www.icmag.com/ic/showthread.php?t=50454

Also thanks for the link for the pvc components.

I will be starting a grow journal probably this week for my first indoor photo grow in the Photo Growing section. I will let you know when I do when and post a link in case you want to check out another old dudes grow. :D:

Going to be growing in TLO super soil to start with, but also researching building a 8 plant hydro table as well, so I'm extra stoked to watch your grow!

Can't wait for your next update.

Take care and stay safe bro! :peace:
 
The Lucas Formula in post #11 has been modified, so the actual from Lucas was added above it. Gonna keep it real here. I kept the modded underneath it for the other info it contains.

Also, as an FYI, I forgot to put a little background in the main post.
I used to grow photos way back in the day. This is my first in 30 years and my first hydro. I've also worked 15 years in the commercial horticulture industry as a residential and commercial applicator/technician.

Also, AGAIN, MANY MANY thanks for the LOOKS LIKES AND REPS!
:hug:
 
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Best of luck with your grow Tx, from the looks of it you will do very well. Good planning and preparation saves a lot of hassle on the back end.
 
Just stop to give you this.... Good-Vibes.jpg........:stylez rasta smoke:
 
UPDATE 11/28/13

HAPPY THANKSGIVING!!!!!
"Munch"

Awright folks!! The Bucket 'O Death is in and the GrowRocks (nope not hydroton) have been soaking for 48 hrs in pH'd and oxygenating water. The rocks were rinsed and rinsed and rinsed again, then soaked for 24 hrs. The water was then pH corrected back to 6.0 and soaked for 24 hrs more. Today a slight correction down to the current levels below:

EC = 511 ppm (up from 395 due to the suspended silica from the pumice GrowRocks, I assume, yes you can see cloudiness).
pH = 6.0 right on the money. No additives or nutes.
Remember, tap water EC = 395 @ 7.5 pH
Ok, guys, I'm really expecting you to chime in on this. As I'm already starting with a moderate ppm with silica in the tank, I guess I should expect a higher than normal range ppm with nutes added? I expect some silica uptake as the plant grows, therefore the overall "normal" range may change along the way. I figure if I go easier on the nutes as it goes along, say, a 5% reduction of calculated addback every few weeks to compensate to reduce the threat of nute burn or lockout. Or would that be necessary?

I'm still waiting for the PVC fittings, but that's no biggie, I'm starting up anyway. Another few days and the frame parts will be here and I'll build out. But til then, I'm going into production. Hope to drop the beans before weekends over. I will say that pumice will not be my first choice of media just due to the fact that they break down easily and I foresee that they won't last long. Before I use the bucket again, I'll get hydroton, but since round 2 and all subsequent rounds will be coco-perlite in 30L tubs, I won't need it anytime soon.

ON TO STEP 2. CLOSET BUILD-OUT!!

Fish
 
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LUCAS FORMULA (Part 2 - Addback Calculations) *from the ASK LUCAS site

------WARNING: THIS ADD BACK SOLUTION BELOW MAY BE TOO AGGRESSIVE AND MAY BURN PLANTS!!!!!--------

Forget the damned addback solution. It may be too agressive and I WON'T BE RESPONSIBLE FOR BURNING SOMEBODY'S BABIES!!!! USE THE SPREADSHEET BELOW IN POST 25 AS IT IS MORE ACCURATE AT THE PERCENTAGE RATE SPECIFIED OF 33%.
SEE POST #25 FOR CONSERVATIVE SOLUTION!!!!
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The Lucas Formula: Addback

the markup formula uses the target tds, and a current tds, to calculate the percentage difference, then use that percentage to multiply against the 8ml that produces the target

so if for example the target is 1300 and the current is 900 with a 50 gallon res it maths out like this
target/current-1*8*Res Size=how many ml of nutes to add to the res
1300/900-1*8*50=178 total ml of nutes to add to the res


this formula is much more accurate than a 33% addback. It is based on markup math, and produces a nute dosage that will tend to be slightly too much, the TDS will be overshot.

***Addback solution (conservative) below: Per documented formula DOES NOT JIVE!!!!!!***

the inverse formula, using markdown math, produces a more conservative estimate
it goes like this
1-(current/target)*8*res size=total ml of nutes to add to res
what counts is to get enough nutes added back to get up to the target TDS, of 1300-1400
the two formulas are predicting that to raise TDS 400 points will take between 125 to 172ml of nutes
once you do it once, it will be the same the next time... you just need to get into the ballpark, or raise TDS in steps..


> with the add back are you also adding water?
good question
the reservoir should be topped up with water before taking a TDS and pH reading
Only After the reservoir is full, should you take TDS and pH readings, and add nutes. With the 33% addback approach, you can nute the water before it is added to top up the res, but it wont guarantee that the TDS will get back to 1300, you may still need to add additional nutes..
for example, some light to res ratios require 100% nuteing of the addback water, in order to achieve 1300TDS the nute in the addback water approach, involves mixing nutes in the water that is going to be used to top up the reservoir. The benefit in DWC, is that you dont have to pump out, to dilute the nutes being added to the root zone.
Do not add pure undilited nutes to a DWC root zone, it will kill roots, and can cause entire plants to suddenly droop and die.
some warnings
in Ebb flow it is safe to add pure nutes to a res, but in DWC it is NOT safe to add pure undiluted nutess to the res that has roots in it
in order to nute a DWC container, it needs to be pumped out into a non root holding container, or at least several gallons worth.

Then the nutes get diluted in the pumped out water, before putting the nuted water back into the DWC root zone.
>The life of a rez on add back?
> what is your opinion of maintaining a setup, be it veg or bloom, at a target TDS for multiple crops without a rez change?
I believe it is possible to go 3 crop cycles on the same res, before pH becomes more difficult to manage, and an unreasonable amount of pH down is required to keep the res within the working pH range of 5.2-5.8 for a DWC type root zone, where they are always wet.
If the roots were in ebb flow, I would move the working pH range to 5.5 to 6.5, because when a pot of medium dries out in an intermittent irrigation system, nutes become concentrated, and pH drops in the root zone, to the same target as the constantly irrigated roots thrive at.
That is my best explanation to why there has always been a persistent belief that plants in soil or soilless medium, need a pH of 6.3 instead of a hydro pH of 5.3.. betewen irrigations the nutes concentrate and the pH drops
tangent, the bacteria that digest raw organic material, and turn it into water soluble nutes, like a pH above 7
back on track
How can we determine when a reservoir has passed its Useful Life? I think the length of time will depend on the size of the res.

For example, I think a 100 gal res for a 1k, will last longer than a 25 gallon res for a 1k.
so what are the parameters that will help us notice when our reservoir is "expired"
this assumes the res is kept full by an autotopping system, and that TDS is kept near original values, by adding nutes. This also assumes RO water. If you use tap, the buildup of calcium will require excess amounts of pH down, and the plants will get P overdose problems
1. The plants look like they are suffering, downcurl leaves, lack of lushness, lack of greenness, spotted leaves, lack of vigor, low yield, etc. Dump the res.
2. If there are no bad health symptoms, and yield does not drop, all else being equal, the res is not expired.
3. An aging res will get out of pH range, and require too much pH adjustment. Generally, with RO water, which adds no calcium, there will be a very slight pH increase over time, this is from unused P and K I think. Im under the impression the plant grabs all the N, which makes pH drop, and leaves a lot of the P and K in the res.. (someone help me out with the science, looking for + and - signs from the growing hydroponic tomatoes publication by Papadopolous.., the valence of the nutrient ions)
anyway, if a res becomes difficult to keep the pH down, dump it
beware a res that suddenly has very low pH, in the 4's. it can happen very fast if roots are rotting and dying. Do not use hydroguard to cure this, what is needed is more oxygen. A bubbler that works fine in the winter but has trouble in the summer, has too small an airpump.. use 1 watt of airpump per gallon of water, and you wont have temp problems until you get above 74F.. I digress, btw, ebb flow has no problem with 80F nutes..
background
plants dont really eat and excrete like organisms with digestive tracts. plants are the unique interface on earth, that captures and packages sunlight, for all the other Carbon Based Organisms that populate the globe
but when pH down interacts with alkaline substances like calcium, the two oppositely electrically charged ions bond and cancel out to a neutral salt, which forms a sediment.. I think its harmless, but, it looks bad, and can be syphoned out
I think the biggest issue with a single source nutrient though, is that there will be accumulations of nutrients of some types, that are underused, and build up in the res.
If anyone does any testing on res life, I would love more data... commercial greenhouses, Im told, dont dump their reservoirs, but they have nute dosers that can add N or P or K individually, and they can test for buildup of individual nutes
those are the parameters I think that need to be monitored, with pH being the canary in the mineshaft.. and where Yield is the final criteria
> (Advanced-Nutrients)

Those are very high quality nutes, use them the same as you would GH Flora series.. and note that you CAN use standard GH nutes recipes, that is 15g-10m-5b for veg, and 5g-10m-15b for bloom, where g is grow, m is micro, b is bloom, and 15 means milliliters per gallon..

there are reasons to believe that the "Lucas Formula", which was pH's idea, not mine, lacks nitrogen in veg, and that even extra nitrogen in bloom can be very productive..

there is no one nutrient that has the magic.. the magic is in the veg time, and CO2 delivery (airflow)

> That would be a profound discovery to me if it's true that FloraGro leaves the res sitting at the ideal ph

:-), there is no magic bullet, but, if you are finding that Grow makes your pH more stable, just do it!

fwiw, what makes Grow different is that it has a different Nitrogen profile..

that is, Micro is 5% Nitrogen, of which 4.7% is Nitrate, and .3% is Ammoniacal, whereas Grow is 2% nitrogen, of which 1.75% is Nitrate, and .25% is Ammoniacal.

Ammoniacal nutes tend to drive pH in the opposite direction of Nitrate nutes..

in any case, Ive come to the general conclusion that more nitrogen than 0-8-16 provides is not a bad thing.. You can do well by just following stock GH directions, if you already own the Grow bottle..

Let me put it this way.. with 0-8-16, Ive yielded .57 grams per watt in 50 days. Using Flora Nova Grow to veg (same as 15-10-5 in flora series), not changing the res, and doing all addbacks with Flora Nova Bloom (same as 0-8-16) I got my best yield ever, .79 grams per watt, in 50 days.

I think more nitrogen than 0-8-16, especially in veg, makes the buds fatter. The stems were much bigger in diameter too.. and the leaves were bigger and greener..
 
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UPDATE 11/29/13

Well, the bucket is ready.

EC = 495 ppm after 72 hrs running
pH = 5.5 and ready for nutes.

Nutes added to the bucket using Lucas for HID @ 0-8-16.
24ml = micro
48ml = bloom
EC = 1400 ppm
pH = STILL AT 5.5!!! Now what is up with that? Guess the nutes are buffered (likely) or pH neutral (not likely)???

Would like some Hydro Heads comments about the EC, please and tell me what you think.
Tap = EC 395 and 7.5 pH and after grow rocks EC increased to 511 (settled @ 495 ppm) pH to 6.5.
pH down applied to = 5.5
So nutes added 1100 ppm to the mix. The 1400 ppm seems right in line with the 0.7 conversion.

Beans drop tomorrow or Sunday into paper towels and then into perlite cups to start until two leaf sets then into the bucket with the best 4.

Fish
 
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