Need help setting up an A/C controlled sealed grow room

[Ricod306]

Good day gents hope all is well given our dire global condition.

I have a few questions.

First, here is what my set up will be:

• 1.2mx2.4mx2m grow tent.
• 9000 BTU air conditioner
• 800W LEDS cooled by by active coolers
• 8x 5gal bottom fed fabric pots (evaporation minimized by pot covers)
• 2x Ram clamp oscillating fans for air circulation

My environment is very hot in the summer(85F</30C<) and very cold in the winter(65F>/20C) and very seldom in between. It has been late summer-early autumn and the temps was still averaged at 28C/82.5F. This yielded in turn very airy buds which I am not looking for. So my only option is to install an A/C system as it is my best way to control my grow tents temps especially with 800W LEDS. The pro is I already have a portable a/c at hand and can easily modify it to act as a split unit (zero air exchange). Thus I wish to set it all up in a complete sealed grow tent.

Issue is CO2

I don't want to buy a tank setup due to their expense in my country, what I do wish to know is will mycelium co2 bags be sufficient enough to run such a set up.

 

[TorturedSoul]

very cold in the winter(65F>/20C)

If that's "very cold," you'd have frozen yer tits off in the warmest room of my house during any of the last... many Winters .

800W LEDS cooled by by active coolers

Could you explain the above, please?

My environment is very hot in the summer(85F</30C<)

If you can keep your grow space at that temperature or even a degree or two higher without active air conditioning - and are able to provide sufficient light-energy to support optimum growth at that temperature, you shouldn't need to go cooler, IMHO. And if you're planning to add supplemental CO₂ to your sealed grow space - and, again, are able to provide sufficient light energy to support optimum growth with that (which is, depending on exactly how much you're raising the level of CO₂... a good bit more light), then you'd actually want your lights-on temperature to be somewhat higher.

 

[Ricod306]

By 800w active coolers I mean they are cooled by heatsinks with fans unlike passive chip coolers as each chip will be 100W, thus having a combination of 8 in 2 pairs of 4 for each half of the tent.

I understand what you are saying about the temps but I have had airy buds through all my grows thus far. And my light is perfect, humidity and temperature is the only variables I don't have much control over especially humidity.

With my previous grow
(very concentrated thc levels) my temp averaged at 25C as it was during winter so the heater and heat from the lights was able to heat the tent. But I think the humidity was a bit low as it was a ceramic heater. The yield from this grow was strong and tasty and very smooth but it was very airy buds, I could grind the buds in my hand by ease(although very sticky due to the trichomes). I never needed a grinder to roll a joint. Unless this is the perfect bud density.

So I really don't know what to do. Could the lack in humidity be the cause of airy buds?

And finally if I wasn't mistaken I thought 25C is the ideal temp for cannabis plants.

And my concern in a sealed room is that Co2 concentrations will drop if I don't add co2 to the environment hens no co2 air will come from the outside of the tent as my light cycle will be 18-6.

Or I'd rather take suggested set ups with the equipment I have and to optimize them. I am also open to buying a humidifier and dehumidifier and a humidity controller to better control my humidity (I want this set up to be optimized for the perfect buds consistently as I sell my yield).

P.S. one of the reasons for using the a/c was also being able to control humidity with a humidifier and humidity controller as the a/c dehumidifies thus I only need to add two component to the equation for humidity control

 

[The Celt]

The ideal temperature for the average grower is 85F or 30C with LEDs, ideal RH is 50% +/- 10% through the entire grow.

If you are getting airy bud under these conditions, my guess would be that it was strain related.

 

[TorturedSoul]

If you are getting airy bud under these conditions, my guess would be that it was strain related.

That, or the fact that 800 watts of light in a 31 ft.² area works out to only 25.8 watts per square foot.

 

[The Celt]

Ya that didn’t help, miss read his first post and thought it was a 4x4 not 4x8 lol

 

[Ricod306]

So if it is 280W per square meter is it not enough? So If I keep the temps at 30 will they be fine then? And the strain was Jack Herer

 

[The Celt]

Well being a Sativa dom strain and not nearly enough light explains your airy buds.

LEDs are great for growing but due to less penetration power, canopies need to be spread out and the light kept close to the canopy for good dense bud.

I run 2 x 630w DE CMH lights in my 4x8 tent. These lights have about 18” (450cm) of penetration. In my seed tent which is 32”x32” (80x80 cm) I have a 4 x 100w 3200k LED that I run at about 410w, anything 12” (30cm) below the canopy is pretty much fluff and if my canopy is dense, will eventually just die.

 

[The Celt]

And no, 280w of LED light per meter is not nearly enough light, especially with those temps.

 

[Ricod306]

Then how much light do I need in terms of watt per square meter and at what temps? The interior of the tent is white which is proven to give more canopy penetration and light spread.

 

[The Celt]

Rough estimate for LED light requirement would be on the order of 350w/m2 minimum but without a light meter to see the actual intensity and spread, that’s about the best advice I can give. Wattage of light isn’t a real good indicator of the quality of light your plants are receiving. 2 lights with the same draw (wattage) can be totally different In terms of quality.

If your temps stay in the 30C +/- 5 you will be fine.

What is the light you are using?

 

[Ricod306]

I forgot to add these LED's are DIY. Chip, lenses, driver, heatsink everything was bought separately and assembled. They draw 100W from the wall +-95% efficient drivers.

Here is just 200W of these LED's 2 chips

 

[The Celt]

If those are 100w COBs that look like this

you will want 10 to 12 in a tent that size.

If they are this kind of COB

You will want a minimum of 18 in that size tent.

The first type has much better penetration than the second and is what I use in my flower tent, the second I use in the nursery.

 

[TorturedSoul]

32, being run at 50 watts per COB, one per square foot (0.092903 square meter), FtW.

 

[The Celt]

The numbers I gave you were minimums, personally, I run 4 in my seed tent giving me about 58w per square foot but it is dimmable so can be turned down during veg.

I rarely use the 50w/sqft theory, that is old school and based on HPS lighting which is much less efficient than LED. I use a light meter and shoot for 35000 Lux or more which translates into just under 600 ppfd. In flower, your ppfd should be a minimum of 500 and up to 1200 depending on your setup and strains you are growing.

Anything over 900-1000 ppfd requires hotter temperatures and supplemental CO2 for the plant to make use of the extra light.

 

[TorturedSoul]

I rarely use the 50w/sqft theory, that is old school and based on HPS lighting

...and indica gardens, or at least indica-leaning hybrids. Equatorial sativas, I'd want at least 62½ watts per square foot.

less efficient than LED.

Well, yeah, depending on the method of gardening (if the canopy is dense enough, I'd want HID). However, I read a year or so ago over at that unsavory (lol) that someone (GrowMau5? I don't remember) had done some experimentation and determined that it was the sweet spot for COBs, too. When using Cree 3950s, IIRC. I wasn't living the stuff, so I don't have the exact details fresh in my mind.

I use a light meter and shoot for 35000 Lux

Wow, talk about old-school. Given two lights of equal efficiency, I'll take the one that produces less lumen, thanks. Plants aren't using the Eyeball, Mark I, Human to gather light-energy with - and the lumen / other measurements based on same is heavily weighted towards portions of the spectrum which appear brighter to our eyes. Such as... green .

In flower, your ppfd should be a minimum of 500 and up to 1200 depending on your setup and strains you are growing.

Anything over 900-1000 ppfd requires hotter temperatures and supplemental CO2 for the plant to make use of the extra light.

Every "maximum usable light under ambient CO₂ conditions" report/article/thread I've seen referenced - if it gave any source at all, and not just another such article that referenced... - the same experiment that was performed some years back. And I remember, back when it was published, that there were five or so reasons why it should only be considered the most preliminary of works, something to build on rather to... bet the farm on. But, with that disclaimer, yes.

In a perfect world, each and every one of us would have an Apogee MQ-500 Full-Spectrum Quantum PAR meter. But, wow, they're not cheap. Many of us can't afford one, and for the rest, well... $538 will buy another light .

That's another reason for worldwide legalization of cannabis! If that were the case, someone - like the owner of this forum, for example - could buy one or more of the things and rent them out to the members, charging a small, but reasonable fee (and taking a suitable deposit, of course). It's not exactly a tool that a person needs on a daily basis.

 

[Ricod306]

Well to put it into perspective I cant look at my hand roughly 50cm away from the light due to its brightness but it does not look like a cheap bought chip like shown. It looks much more like luminus's cxm 18 chips....

And yes I have done a shit ton of research on COB's and I have the perfect one in mind (Same chip as the Migro100 LED's)
Btw anyone not knowing this, Luminus's cxm gen 4 LED's are by the far the best on the market right now for indoor growing. Their 4000K LED has the perfect light spectrum range for plants. Perfectly in the red and blue and both equally balanced and highly optimized at 90 to 95 CRI. These COBS are very expensive though like $50 a COB and then the max output per COB is 100W and 16K lumens and then it's pushing it's limits.

I know my lights might not be the best but i'm trying to get there. Still to my main question about co2 levels in a sealed tent. What will happen if no fresh air is circulated into the tent will I need co2 adding.

 

[The Celt]

Wow, talk about old-school. Given two lights of equal efficiency, I'll take the one that produces less lumen, thanks. Plants aren't using the Eyeball, Mark I, Human to gather light-energy with - and the lumen / other measurements based on same is heavily weighted towards portions of the spectrum which appear brighter to our eyes. Such as... green .

Actually, LUX, is a very good indicator of light quality in regards to our plants if you know the spectrum of your light. 35000 Lux translates into a PPFD of 595 for 3200k white LEDs. Apogee lists conversion factors for multiple light sources on their website. You don’t need a $2500 Quantum Meter to ball park the PPFD.

Every "maximum usable light under ambient CO2 conditions" report/article/thread I've seen referenced - if it gave any source at all, and not just another such article that referenced... - the same experiment that was performed some years back. And I remember, back when it was published, that there were five or so reasons why it should only be considered the most preliminary of works, something to build on rather to... bet the farm on. But, with that disclaimer, yes.

In a perfect world, each and every one of us would have an Apogee MQ-500 Full-Spectrum Quantum PAR meter. But, wow, they're not cheap. Many of us can't afford one, and for the rest, well... $538 will buy another light .

As for what light levels when, that info I shared came from Dr Bruce Bugbee who is a hemp researcher/professor at Utah State University and also the founder of Apogee. He has quite a number of very informative videos and I suspect he knows more about plant (and cannabis) physiology than the whole lot of us combined lol

 

[Ricod306]

Well to put it into perspective I cant look at my hand roughly 50cm away from the light due to its brightness but it does not look like a cheap bought chip like shown. It looks much more like luminus's cxm 18 chips....

And yes I have done a shit ton of research on COB's and I have the perfect one in mind (Same chip as the Migro100 LED's)
Btw anyone not knowing this, Luminus's cxm gen 4 LED's are by the far the best on the market right now for indoor growing. Their 4000K LED has the perfect light spectrum range for plants. Perfectly in the red and blue and both equally balanced and highly optimized at 90 to 95 CRI. These COBS are very expensive though like $50 a COB and then the max output per COB is 100W and 16K lumens and then it's pushing it's limits.

I know my lights might not be the best but i'm trying to get there. Still to my main question about co2 levels in a sealed tent. What will happen if no fresh air is circulated into the tent will I need co2 adding.

Thank you all for the input but I did the research and know the science behind lights,plants and how they all come together but at the moment these are what I've got. But this could be the cause to my airy buds as these lights I have now are very bright but i do not take them as efficient in terms of ppfd and so forth. And I chose my future chip via spectrum charts and scientific articles about plants and how they processes light.

I still wish to know about the co2 levels in a tent. My main concern at this moment is environment control for these plants and keeping it constant to reduce stress for my plants.

 

[The Celt]

OK, so here’s what we know: temps are fine but your lights are lacking for that much area.

What we don’t know is the medium you grew in and what if any nutrients you used. Pictures of the plants with airy buds would be immensely helpful as there are other factors that could be at issue.

Too much nitrogen during bloom can cause airy buds and other issues, for example.