CO2: Sealed Room or with Fresh Air?

Ive got a question here I am having a hard time finding the answer too. Room is about 10x15 or 10x10 feet. I have questions about CO2.

Am I better off sealing the room from the outside environment like Tranoble has done, and generating CO2 from something like a Blue Ox or a tank?

Am I better off pulling in constant fresh air into the room while quickly exhausting it back out in a different location outside, but not using any CO2?

Or am I better off pulling in fresh air and exhausting it, and using CO2 in conjunction?

I am new to CO2 but was under the impression that you can benefit from CO2 even if you have fresh air as well. I assume it is not as important as with a sealed room, but if it will help fill out the buds then I would love to do it. So is a CO2 generator better then a CO2 tank? I mean...how much worse are tanks? I already have 2 CO2 tanks from other hobbies (they are about the size of a SCUBA tank). I havent done the math but how long would they last to achieve the approximate ppm results I want?

Then comes the inevitable question of how to do the CO2. I figured the best way would be to have constant fresh air moving through the room, then for specific periods of about an hour, shut the fans off, release the CO2 and let the temps raise (4 1000watt HPS so that shouldnt be hard), and then exhaust the CO2 and bring fresh air back in. I assume I must shut off the fans whether its a CO2 generator or a CO2 tank on a constant seep cause otherwise it wont be utilized? CO2 controllers are not very expensive.

I guess when it comes down to it, if a sealed room can produce just good results as fresh air if it has an A/C, dehumidifier, and CO2... then it sure its nice to have the safety and control over the environment.

Co2, great stuff. Green air products and CAP make controllers that control the ventilation in your room for co2 enrichment. Are your lights air cooled? I would go with air cooled hoods to keep them on their own system to better control the heat. Make sure they are tight with nashau metal tape. You'll want to still use fans to keep the air circulating inside the room and use the soaker hoses draped above your plants to deliver the c02 as co2 is heavier than air. There is an equation for c02 enrichment in Ed Rosenthals book. I'll have to find it fer ya.

co2 with controler, venting when off
higher room temps for co2 absorbs better. vertical fan to move air from the floor
distrubution of co2 around the room when made, via a small box or ventury fan
When night comes pump out the air, as plants make co2 at night.
If you look at my gallery, the system is automated, to maximize everything
Note that its even recorded to make sure no failures of any system.
sharprubberduck.net note net.
smell atimizers are automatic, a must when it comes in to bloom stage.
some air is scavanged off to the grow room.
automation make life real simple and efficent , pot is like hookers , if its not putting out , its out.
I used both gen and bottle , gen when temps required warming up and bottle when ambiant temp was to high.

Thanks a lot guys for the advice. I definitely do not and will not have a problem with low tempatures. If bottles can last long enough and be somewhat cost effective, I will just deal with that since there isnt a natural gas or propane hookup in the room. I am an avid welder so they know me at the welding shop, buying a lot of co2 is chill. I am also using air cooled hoods.

My next question is...how long to let it soak without the fans? An hour? How many times a day?

I dont think I will play with a ring above the plants unless there are serious advantages, although that would be rather easy to make with a torch. I like the idea of a light-action fan moving it up into the air from the floor, but it wouldn't be hard to run a line to the ceiling.

And I was slightly confused by your remark about the night. At night plants produce their own CO2, so I dont need to worry about it? Is that what your saying?

This should help you some.
http://www.hydroponics.net/learn/co2_calculator.asp

The idea is to raise the level up to around 1500 PPM to 1800 PPM and hold it there for hours. Then exchange the air in the room and do it all over again. While the CO² is on you must have a sealed room or you waist the gas. The calculator link I gave you only calculates the amount it takes to reach the number and does not count how often you need to fill. That depends on how much your room leaks, how much the plant uses. You can figure that with a PPM controller or one of those syringes that measure the air and give a reading on colored paper.

The plant can only process the enhanced CO² with the lights on and you should use HID lights as well. In the dark cycle there is no point in using enhanced CO² the plants can't process it.

Fluorescents lights are no good for use with CO² they do not produce enough light for the plant to process the extra amount in the air.

Your plants will drink up a ton of water when you start using CO² so be prepared for that as well as how much larger the plants will get. The extra temperature needs to be controlled properly and don't let it get to hot. It's a fine line to walk but well worth the effort in the long haul.
Enhanced CO² is one of the most effective way's to grow big buds there is today. When you combine that with proper temperature control and humidity you have very healthy, happy large plants.

Zandor, thats a great calculator to get started with. I knew Id seen that around somewhere. This is all good, because I can stay with my original plan. The room will be entirely sealed except for the intake and exhaust. I will use some home made spring loaded trapdoors on the fans so that when they are not blowing they close up. That will really get it sealed.

I am doing about 100 plants at first, and Ill keep the room 10x10x8 until I decide to expand (I have a lot more room to work with but I figure small is good to start with cause you can control temp easier). Can A/C be used at the same time as CO2 to help control tempature? No issues with those messing with eachother? Do I still want my oscillating fans inside the room moving around the CO2 or do I want it fairly still? If I turn off all my intake and exhaust, that means turning off my air-cooled hoods as well (they are connected to the exhaust). So if I am keeping all fans off for a couple hours at the hottest part of the day...it might get pretty hot in there. Do I want to turn off my humidifier when the CO2 is released as well?

Zandor, any preferance on how to distribute the CO2? Will a fan on the floor bring it up into the room be sufficient? Or should I make a halo thing for the ceiling and let it fall? Or just release it on the ceiling? Does CO2 immediatly fall below air like a stone or is it a slower process? I could make pipes for it pretty easily (I am proficient in general construction).

It sounds like my 20 pound tanks will work fine for awhile, althoug if the generators only need a 5 gallon propane tank, thats available everywhere and super cheap. But it seems like heat would be an issue with them and I will be fighting the to hot battle, not the to cold battle.

As for watering. I was just going to hand water with a wand, as this operation is with a partner so generally if one of us are not around, the other is. With a planter box setup, I am expecting to water everyday (just not very much water) and I will use a res with the nutrients already mixed (like Tranoble has done).

Finally...I am making the assumption that for easy of controlling climate and for being as efficient as possible with the CO2, that I want the smallest room I can use for what I am doing?

Bah, lot of questions!