Dehumidifer inside vs. outside tent (with CO2)?

@ Dr. Who -- I love your response. That was simply awesome, I'll probably read it a few more times even.

The goal is all about maximum efficiency. I know that some people grow for the largest harvest, biggest monster buds, others for strain variety, whatever... in this case it's all about searching for peak efficiency. With this setup there are two Saturn 6 Titan controllers with PPM meters on the way for setup to precisely regulate the 20 lb CO2 tank per flower tent. There are two flower tents, 1 veg/clone tent, and 1 harvest/dry tent -- all for perpetual harvest setup. No plans to use CO2 for veg, as you indicated earlier it is not efficient. Just so we are on the same page.

I have a couple follow up questions for you:

1. You mentioned needing enough light intensity to maximum CO2. Is there a general rule of thumb that graphs optimum CO2 PPM to watt/sq ft or lumen/sq ft? This would greatly help someone know how to achieve efficiency when setting their CO2 per tent based upon the available light.
   
   In the first flower tent there are (2) 400 watt HPS air-cooled plus (2) HLG QB 324 V2's (~165 watt each x 2) in a 20.5 sq foot space, which is about 55 watts / sq ft with 30% of that being high efficiency QB LED light. In the second flower tent there are (2) 600 watt HPS aircooled plus (2) HLG QB 324 V2's (~165 watt each x 2) in a 25 sq foot space, which comes out to slightly more than 60 watts / sq ft with 20% of that being high efficiency QB LED light.
   
   It would be very helpful to know how to adjust PPM based upon light added. So if one changes the intensity of their light or makes changes to the available lighting (ie: adding/removing), one would know how to consequently change the atmospheric PPM to match light output. (Almost in the same way that you graph the VPD temp. and humidity relationship above)
   
   
2. Not to be confused with the previous question, what do you feel the peak efficiency light range is for growing with and without CO2? I know that you can continue to throw more and more light at your plants and continue to see larger and larger results, however Maximumyield commercial grow articles indicate that there is a diminishing return beyond a certain watt per sq feet, generally speaking. I was curious what that light saturation point is before the bell curve begins to become less and less efficient with each added watt of light. Some estimates suggest 60 watt per sq foot of HID light or 25-30 watts per sq feet of LED (depending upon chip efficiency). How do you feel about that? Do those numbers seem accurate based upon your experience?
   
   
3. You seem to also be growing for peak efficiency; the best use of every resource, every dollar, and every amount of time for the maximum return. Most commercial growing articles recommend SOG for peak efficiency. I'm curious how you feel about that and how many plants you grow per sq. feet. I'm also wondering what length of veg time you provide.
   
   
4. I can see from your post that one needs to follow this VPD chart to maximize their CO2/light efficiency. That makes sense. There's a laser thermometer that can help keep an eye on things in conjunction with the other equipment. That said, with a higher RH %, how best does one prevent mold and bacteria growth during the mid-late stages of flower?
   
   
5. If I am understanding your post above, one would need to use more nutrients (in other words a higher concentration of ppm or EC) with injected CO2 while following the VPD chart above, not only to adjust for the increased plant growth but also because of the decreased water uptake from the roots. Or do I have part of this backwards? [Scratching my head...]
   
   
6. Why did you stop using CO2? If not in the 1100 range, why not at even a 600-900 ppm range? Ed Rosenthal put it simply when he said, "If you're not using CO2 then you are wasting your light energy" (not an exact quote). I'm wondering why you stopped using it all together?

Thanks again for the help and thoughtful responses! Very educational and helpful.

told you the Doc knows what's up. lol.

here's an article to peruse for ya:

https://www.ncbi.nlm.nih.gov/pubmed/23572895

you''ll need a Lux meter (pretty cheap on ebay) to roughly convert what you got as far as ppfd goes.

rkymtnman said:

told you the Doc knows what's up. lol.

here's an article to peruse for ya:

https://www.ncbi.nlm.nih.gov/pubmed/23572895

you''ll need a Lux meter (pretty cheap on ebay) to roughly convert what you got as far as ppfd goes.

Click to expand...

Good info. The journal concluded that:

So it sort of answers question # 2 listed above:

1500 umol throughout the grow room and between 25-30 degrees Celsius without added CO2. If I'm understanding this properly than with CO2 between 1500-2000 u mol are benefited in a drier environment. However, we know from @Dr. Who earlier post, that you do not want a drier environment with CO2 increases.

here's a wrench to throw in;
the study was for sativas. how about indicas? how about hybirids? how about 70/30 sativas? how aout 80/20 indicas? etc.

i would say your first step is to get an idea of what your ppfd is at. i need to measure mine again now that i have new qbs.

Since it was medical journal type format I had assumed they used the formal name of the plant Cannabis Sativa L in the scientific since of the word. They have not provided another subspecies for Indica technically -- even though we all consider it subspecies (as most do) -- science hasn't caught up yet! Will definitely get my cheapo eBay LUX meter out after I get the tents all setup. Curious to know they'll be at peak efficiency and then too what CO2 ppm level matches that light intensity.

I'm hoping @Dr. Who will get a chance to look at some of my other questions when he gets a chance.

jjng5 said:

Since it was medical journal type format I had assumed they used the formal name of the plant Cannabis Sativa L in the scientific since of the word. They have not provided another subspecies for Indica technically -- even though we all consider it subspecies (as most do) -- science hasn't caught up yet! Will definitely get my cheapo eBay LUX meter out after I get the tents all setup. Curious to know they'll be at peak efficiency and then too what CO2 ppm level matches that light intensity.

I'm hoping @Dr. Who will get a chance to look at some of my other questions when he gets a chance.

Click to expand...

he's a morning guy.

what i did wiht my co2 was just gas it during flower for about double atmosphere levels. or about 800ppm. i dont' care about cost, ROI or that other crap. just bigger buds for few bucks more a grow made me ha[ppy.

@rkymtnman I get that. To each their own -- in this case part of the fun is to see how hard one can push the limits of the system to it's peak efficiency and then continue to improve a little bit more, and then a little bit more, etc. Alter training techniques slightly, change the environment a little, nutrient levels, etc. That's sort of part of the fun of it all I think. For the money already spent in QB's, CO2, HPS, controllers, ventilation, tents, nutrients... anyone could have just bought 3 x 1k air-cooled HPS lights and jammed thenm into a 4x8 tent, dropped some seeds into soil buckets, and grown massive bud.

But in this case it's sort of fun to keep track of Co2 ppm, nutrient ppm, atmospheric values, use lux meters, and laser thermometers to determine VPD, then at the end weigh and see what your gram per watt was and then set a new goal for next time and tweak one or two small things to determine if it had a desired impact. If not try something a little different.

rkymtnman said:

told you the Doc knows what's up. lol.

here's an article to peruse for ya:

https://www.ncbi.nlm.nih.gov/pubmed/23572895

you''ll need a Lux meter (pretty cheap on ebay) to roughly convert what you got as far as ppfd goes.

Click to expand...

Interesting abstract....Be SURE to click the link on the right to the whole paper! It brings you to the abstract page with a PDF download link for the whole thing!

You should read that and it better covers the experiments you see the conclusions with the real information....

jjng5 said:

@ Dr. Who -- I love your response. That was simply awesome, I'll probably read it a few more times even.

The goal is all about maximum efficiency. I know that some people grow for the largest harvest, biggest monster buds, others for strain variety, whatever... in this case it's all about searching for peak efficiency. With this setup there are two Saturn 6 Titan controllers with PPM meters on the way for setup to precisely regulate the 20 lb CO2 tank per flower tent. There are two flower tents, 1 veg/clone tent, and 1 harvest/dry tent -- all for perpetual harvest setup. No plans to use CO2 for veg, as you indicated earlier it is not efficient. Just so we are on the same page.

I have a couple follow up questions for you:

1. You mentioned needing enough light intensity to maximum CO2. Is there a general rule of thumb that graphs optimum CO2 PPM to watt/sq ft or lumen/sq ft? This would greatly help someone know how to achieve efficiency when setting their CO2 per tent based upon the available light.
   
   In the first flower tent there are (2) 400 watt HPS air-cooled plus (2) HLG QB 324 V2's (~165 watt each x 2) in a 20.5 sq foot space, which is about 55 watts / sq ft with 30% of that being high efficiency QB LED light. In the second flower tent there are (2) 600 watt HPS aircooled plus (2) HLG QB 324 V2's (~165 watt each x 2) in a 25 sq foot space, which comes out to slightly more than 60 watts / sq ft with 20% of that being high efficiency QB LED light.
   
   It would be very helpful to know how to adjust PPM based upon light added. So if one changes the intensity of their light or makes changes to the available lighting (ie: adding/removing), one would know how to consequently change the atmospheric PPM to match light output. (Almost in the same way that you graph the VPD temp. and humidity relationship above)
   
   
2. Not to be confused with the previous question, what do you feel the peak efficiency light range is for growing with and without CO2? I know that you can continue to throw more and more light at your plants and continue to see larger and larger results, however Maximumyield commercial grow articles indicate that there is a diminishing return beyond a certain watt per sq feet, generally speaking. I was curious what that light saturation point is before the bell curve begins to become less and less efficient with each added watt of light. Some estimates suggest 60 watt per sq foot of HID light or 25-30 watts per sq feet of LED (depending upon chip efficiency). How do you feel about that? Do those numbers seem accurate based upon your experience?
   
   
3. You seem to also be growing for peak efficiency; the best use of every resource, every dollar, and every amount of time for the maximum return. Most commercial growing articles recommend SOG for peak efficiency. I'm curious how you feel about that and how many plants you grow per sq. feet. I'm also wondering what length of veg time you provide.
   
   
4. I can see from your post that one needs to follow this VPD chart to maximize their CO2/light efficiency. That makes sense. There's a laser thermometer that can help keep an eye on things in conjunction with the other equipment. That said, with a higher RH %, how best does one prevent mold and bacteria growth during the mid-late stages of flower?
   
   
5. If I am understanding your post above, one would need to use more nutrients (in other words a higher concentration of ppm or EC) with injected CO2 while following the VPD chart above, not only to adjust for the increased plant growth but also because of the decreased water uptake from the roots. Or do I have part of this backwards? [Scratching my head...]
   
   
6. Why did you stop using CO2? If not in the 1100 range, why not at even a 600-900 ppm range? Ed Rosenthal put it simply when he said, "If you're not using CO2 then you are wasting your light energy" (not an exact quote). I'm wondering why you stopped using it all together?

Thanks again for the help and thoughtful responses! Very educational and helpful.

Click to expand...

#1: No. It's an up slope scale that increases like a bell curve. The more ppm's the more light energy is required. At "sort of like" an exponential rate increase.... As you move from the 1300 ppm (pretty much a growers limit) to 1500 ppm, The increase in light energy needed to make that work.....Is a massive increase (of light energy) over the same 200 ppm increase from 600 to 800 ppm.

Understand?

#2: I'm running 1400 w of HID per hood. Each hood has 20% more reflective power then "normal" hoods(they have reflector material over the 6" air cooling holes. These were the best ever made - New designs of the like type are less effective in several ways. Long story)
They are set on 6' centers to overlap for better efficiency.
I'm around 80 w+ per sqft.... If I figured it right...
Light saturation point in Cannabis, in the wild. Is far earlier in the day then many think... Gassing allows the plant to run at peak efficiency longer. Nearing that 30+% loss by the plant changing on the cellular peptide level - To actually protect it's self from the sun. The point in the day when the plant begins that change = Light saturation point.....Night time is when the cellular peptides change back to cells being photo receptors.....

#3: OH YES! SOG rules the roost for efficiency! Being limited by #'s and being to old to do real time.....I sadly don't do it any more. I've done SOG testing and gotten over 4 Grams per watt! even in a 4 - 5' tent, you can get over 3.4! Read the post linked below. I basically told everyone how to do it!

https://www.rollitup.org/t/only-experienced-master-growers-please.985106/#post-14763253

I grow to try to reach strain potentials... The best the strain can be. Best pheno's (At least the best that I picked out for my wants)....Efficiency is simply me doing the best without spending more then I need to reach my goals. This is leftover from running greenhouses and massive Yew farms for a drug company.....Efficiency comes by nature to me. I manage a large organic farm co-op now. It has grown beyond what the first 3 of us that banded together, ever thought it would become....We are constantly growing....

a: I generally put 4 plants under a light. It is a single continuing line of plants...No breaks.. Depending on the strains. Some big old school strains (Blue Berry [Muffin cut]) can be a massive plant taking the space of 2 or even the whole 4 plant plant space. The old Blueberry, even with 19-20 % THC is still loved by my patients (and by other breeders).... She has massive BB flavors that even just from the bag. Smell like warm, fresh from the oven, Blue Berry Muffins.

b: Veg time? As long as it takes the plant to reach about just over half the finished plant size... I've been doing this sooo,,,long that I have simply come to moving plants by size. Same for up potting's.
Oh, I would have to guess at about 2 months from clone to bloom...some more, some less....

#4: I have never had a PM or mold issue when I ran gas....Maybe too high an RH? I had the thing set to dump the hot, humid air at lights out too! They sat in 45/50 RH and 65 F at night...
You may find some condensation on the ceiling of the tent.... It never gave me issue. Knock wood - I have never had a bud rot issue but, once outside. That was due to the plant being knocked over and the bud contacting the ground - that did not dry out at night...Got it.

#5: I found you had to watch for over feeding more.... The Co2 increases everything. Higher RH is to keep the plant in the sweet spot for uptake... Now a drier eviro....Would increase uptake as the plant is trying to protect it's self from the heat..... For some reason, it seamed to fuck with mySuper soil/water only organic plants more.....I did more organic liquid nutrient use when I gassed....Easier to control and dial in....Um, that was Age Old organic nutrients...

#6: For the space I run for rooms (12x24x10). I have to run Generators... They work well but, have drawbacks too. Cooling them as they run, space needed for cooling equip. and water tanks, Cost to run all of that....Vs the returns I get... Not worth it in my book.... A savvy grower can up his yields to points where gassing is not really worth his time.....It takes time and real dialing in of strains, pushing the plant but, not going over the cliff on it... Why I like soil over hydro too. I can match hydro yields..it might be faster but, Mine tastes better! MUCH better...

Anything else?

jjng5 said:

Picked up two units (one for each flower tent) -- 30 pint Haier compact compressor style dehumidifiers with drain hose connection on the rear. This should work well with the Saturn 6 controllers on the setting selection where you "unlink" temp and humidity so that it does not dump your CO2 atmosphere when RH % gooes outside the set range, it will only dump if temps raise outside the range.

Take a peak -- $100 each including shipping:

View attachment 4294540


It has handles it says -- going to try and use ratchet straps to hang this thing up-right from the tent, it's only 25 lb's empty.

Click to expand...

I live in the Northeast and just moved the grow out of the basement due to humidity, i was dumping about 85 pints of water a day last summer and it lasted until I got the electric bill and the grow moved out of the basement then as well only to the garage that time. This time I was lucky enough to move it to a spare room!!!!!

... Ugh -- SWIM is looking over credit card statements for the last 6 months in getting everything in place... at around $6k so far! 4 HIDs, cool tubes, three T5HO fixtures, 4 x QB's with drivers, pumps, cords, tools, 5 grow tents, nutrients in bulk plus enzymes beneficials etc, co2 tanks and regulators, (2) environmental controllers, quality seeds and propagation equipment doms heating pads, growing medium, net cupes, cloning equipment, 2 condenser-style dehumidifers, ventilation equipment fans and exhausts, hydro containers, tds/pH meters, humidity/temp meters, a scale, lux light meter, infrared temp. meter, res filter with uv water sanitizer, magnifying glasses, 250 ft grow soft foam training wire, scrog nets for the tents, carbon scrubbers, timers, harvest mesh drying nets, probably dozens of other stuff that's easily looked over. like ratchet straps and whatever else.. lol

That still leaves needing a BHO setup with purge valves, vacuum sealing mason jars, and all the post-harvest toys... jesus before it's really even started it could quickly reach $10k not counting the electricity and water bills...

jjng5 said:

... Ugh -- SWIM is looking over credit card statements for the last 6 months in getting everything in place... at around $6k so far! 4 HIDs, cool tubes, three T5HO fixtures, 4 x QB's with drivers, pumps, cords, tools, 5 grow tents, nutrients in bulk plus enzymes beneficials etc, co2 tanks and regulators, (2) environmental controllers, quality seeds and propagation equipment doms heating pads, growing medium, net cupes, cloning equipment, 2 condenser-style dehumidifers, ventilation equipment fans, hydro containers, tds/pH meters, humidity/temp meters, a scale, lux light meter, infrared temp. meter, res filter with uv water sanitizer, magnifying glasses, 250 ft grow soft foam training wire, scrog nets fro the tents, carbon scrubbers, timers, harvest mesh drying nets, probably dozens of other stuff that's easily looked over. like ratchet straps and whatever else.. lol

That still leaves needing a BHO setup with purge valves, vacuum sealing mason jars, and all the post-harvest toys... jesus before it's even started it could quickly reach $10k

Click to expand...

I hear ya, I probably have well over 60k in my grow. But that said it makes me about that every run.

Renfro said:

I hear ya, I probably have well over 60k in my grow. But that said it makes me about that every run.

Click to expand...

Well, there's that! haha. Still it's a little unnerving in the ramp up period...

jjng5 said:

Well, there's that! haha. Still it's a little unnerving in the ramp up period...

Click to expand...

Yep, any fuck ups and your in the hole trying to climb out. I have one friend who setup his room, spent about 40k on it. He had 4 bad runs in a row, 2000 dollar electric bills and all. He quit for about a year and is trying to start it back up but this time he is listening to me and he is looking good about halfway thru flowering.

@Renfro well that's good. From SWIM been on here on and off for the last 10 years with only really about 1 year of that period consistently growing. First efforts were in soil of course. Then switched to DWC hydro in 1 single 4x4 tent in an apartment under a 400W HPS starter light and shit reflector. From that last run the buds were not dried properly and half of the harvest was lost to mold. LOL. Fast foward many years... there's a viable opportunity and fuck it, go big or go home. Why half do something? Cross your fingers for SWIM if you would Renfro! Lol

@Renfro it sure never feels like $6k one $100, $250 purchase at a time... a couple boxes showing up at your door step off and on. This started out as a coat closet grow, then moved to a 4x4 tent in the apartment living room, and now... is taking up most of an entire basement! And who said that Cannabis wasn't an addictive substance?!

One can see how these hydro shops and nutrient vendors stay in business!

jjng5 said:

@ Renfro well that's good. From SWIM been on here on and off for the last 10 years with only really about 1 year of that period consistently growing. First efforts were in soil of course. Then switched to DWC hydro in 1 single 4x4 tent in an apartment under a 400W HPS starter light and shit reflector. From that last run the buds were not dried properly and half of the harvest was lost to mold. LOL. Fast foward many years... there's a viable opportunity and fuck it, go big or go home. Why half do something? Cross your fingers for SWIM if you would Renfro! Lol

Click to expand...

I have been growing since 1989, wouldn't wanna do anything else. That said when I moved from Missouri to Colorado it was a huge learning curve for me as I was used to high humidity and not this high desert ass climate. I never new powdery mildew existed until I moved here, it never got dry enough in missouri and PM likes the high low RH% swings. SO when I first moved here I had to get smart quick. Just got my first tent on order so I have a space to breed. Honestly all I ever did was whole basement grows, like you said, go big or go home.

W00t w00t! My electricity provider offers $25 rebates per dehumidifier purchases. Has anyone else done this before? For a factory refurbished $100 purchase, $25 off isn't bad!

Cost adds up so quick especially when running a bunch of tents. I’d say I have more in my tent set ups than I will have when finished with my room build. Then what do ya do with all the “old”equipment. My advice to people asking about anything anymore is buy the bigger one or better one. Because rebuying the same shit just a bigger size (or cause the cheap one broke) has cost me plenty. From now on I will figure out what the max KWh I’m willing to show up on a bill from the beginning and just build it accordingly.

Ugh... SWIM is skipping their workout this morning. Lugging 3 x 20 lb CO2 tanks to be filled (not as bad) and then carrying them back home (bad!). If anyone is considering a 35 lb tank or 50 lb CO2 tank... JUST STOP IT! A 20 lb tank sounds light... but it's really 25 lb's with the regulator... and then they fill the tank with another 20 lb's of compressed co2 gas bringing it up to 45 pounds in an akward shape. Oh and did I mention that the entire tank is ICE cold! Yes, next time I will be bringing gloves along... I swear I almost got frostbite by the third tank. The things we do for the women in our lives (...and these are the only women in SWIM's life). Lol