CO2 and cooling questions.

A few things I see as facts when using CO2:

1) Stay under 90 degrees.
2) Don't have to vent the grow at all.
3) Don't need a carbon filter in a tent, but one in the room would be smart.

If these are wrong, let me know.

I have a 4x4 secret jardin tent with a 1000w cooltube. I have a large dehumidifier and a room window unit. I have 2 stanley blowers, 1 vortex fan, and 1 booster. All 6". Currently, the light is run with the vortex fan and it is sucking outside air and exhausting into my attic. I assume that will not need to change. My AC is ducted into the intake of the tent. This seems like it would work fine using CO2 too. The grow exhausts through a Can 33 filter into the room. It seems like my only real need is to duct the exhaust of the tent into the intake of the AC. If I did that, I wouldn't have the dehumidifier in the loop anymore. I thought about it and I don't want to CO2 the entire room.

I thought about it a bit longer and I decided that I could just build a enclosure around the AC and dehumidifier. This would solve all my perceived problems. I can just run the exhaust into the enclosure and then pipe out the cold air back into the grow. Does this sound like a reasonable way to go about this? I already ordered the CO2 valve, and I will go pick up the tank when it gets here. I plan to run without a controller for the first grow probably. Calculating it out will give me ballpark, and then after harvest I will get a CAP controller. I plan to run a CAN 33 filter in the room outside the tent to keep smell down that might escape.

Does CO2 change anything else about the grow?

Am I missing anything?

Are there any other problems I need to face with CO2?

you can reat/lease a 50 lb tank from welding gas supply house for about 50.00/yr. exchange on that empty tank for a full one cost the same as a 10 lb tank exchange at home depot...17.00 bucks in my neck of the woods. this is a very good tip that i found out the hard way.my grow uses about 7-8lbs/ every 12 hr cycle.so a tank lasts about a week. once you get your set up and running you will know what your consumption per cycle is. my grow is [flower] 7'hx7'wx12'd.much bigger than your tent im sure. also, i have a duel hose PAC air cond/dehum. thats whats really needed to keep your co2 in the tent. well, the simplest ive found...good luck!

be prepared to water n feed more... but just cuz u run co2 doesnt mean u dont have to vent the room. u just dont vent it while the co2 is being released. i havent set mine up yet but my boy uses one and he runs his fans and a/c for 2 hours then when that goes off co2 goes on for 2 hours and that continues during the whole light cycle. using co2 during the dark cycle does nothing. i heard the best thing when running all of those is to go get one of those controllers for like 200 or 300 bucks. i saw one that had a plug in for ur dehumidifier, ac, and co2. it controls the whole environment automatically and takes the thinking out of when to run fans and ac and when to run co2.

grow plenty said:

you can reat/lease a 50 lb tank from welding gas supply house for about 50.00/yr. exchange on that empty tank for a full one cost the same as a 10 lb tank exchange at home depot...17.00 bucks in my neck of the woods. this is a very good tip that i found out the hard way.my grow uses about 7-8lbs/ every 12 hr cycle.so a tank lasts about a week. once you get your set up and running you will know what your consumption per cycle is. my grow is [flower] 7'hx7'wx12'd.much bigger than your tent im sure. also, i have a duel hose PAC air cond/dehum. thats whats really needed to keep your co2 in the tent. well, the simplest ive found...good luck!

Click to expand...

I think I have the cooling and humidity under control. Using the calculator here(http://www.hydroponics.net/learn/co2_calculator.asp) with my 4x4x7 tent. It says on time will be about 8-9 minutes to fill the tent completely and that a 20lb bottle will last about 175 hours. If i completely refill the room every hour that is about 100 minutes a day. 175x60=10500. 10500/100=105. I think that means a full 20lb co2 tank will do an entire grow for me if I completely refill the room every hour.

Is this needed? The plants don't use all of the co2 every hour do they? I didn't realize that home depot even had CO2 tanks. I had about 10 20lb ones for homebrewing but I sold all my equipment. Kicking myself now.

southsacboy916 said:

be prepared to water n feed more... but just cuz u run co2 doesnt mean u dont have to vent the room. u just dont vent it while the co2 is being released. i havent set mine up yet but my boy uses one and he runs his fans and a/c for 2 hours then when that goes off co2 goes on for 2 hours and that continues during the whole light cycle. using co2 during the dark cycle does nothing. i heard the best thing when running all of those is to go get one of those controllers for like 200 or 300 bucks. i saw one that had a plug in for ur dehumidifier, ac, and co2. it controls the whole environment automatically and takes the thinking out of when to run fans and ac and when to run co2.

Click to expand...

I have about 50 gallons in my system altogether. The 20 gallon res is set up so that regardless of what the water level is in the res the DWC buckets are completely full and the system continues to circulate. I don't think I will have an issue keeping the system full or feeding the plants.

The reason I don't think I would have to vent the room is because I would have a dehumidifier and AC in the loop keeping the temperature and humidity where they need to be. It will be a closed system.

I may have to break down and get a controller. I don't need one for the exhaust system. It can stay running 24/7. I do need one for the CO2 though. Given my simple needs for a CO2 controller I am looking at the $200 cap one that controls the CO2 levels without any real adjustments. It seems like it would be good enough to keep me in the general range for co2 without wasting the gas.

I run a sealed room, I NEVER vent anything, I was running 1500 ppm's and a 20 lb tank would last 30 days, I lowered my ppm's to 1200 with no difference except for 3 more weeks of c02.
and the cap controller is the cheapest one available cost wise, a good choice for a tent. I personally use a sentinel, but it is twice the cost of the c.a.p

I run a sealed room as well, but opt to vent every 3 hours for about 3 min. My room is about 10x8x6 and a tank of co2 (25lb) lasts about 5 weeks in flower at 1400ppm. I use a cap controller, which sucks but works fine as long as you throw it on a cheap timer that resets the cap ppm3 every so often. (the problem with the cap controller is that it locks up every so often, therefore the work around with the reset).
The reason for venting is not that the plants need fresh air, it is so I don't build up any offgasing toxins from the grow space. I've been growing in a sealed room for over 4 years, tried it without venting as well as with, and in my situation I get the best results with periodic venting. However, had I seen no difference between venting and not venting I would have opted for not venting.

Now, the cool thing I dialed in this winter is not having to run any ac in my sealed room, which should perk up some ears from people that run sealed rooms.