First of all when a cylinder of co2 is only $25 bucks i dont see why people even fool around with anything else. But i have a few questions about concept that i am not sure if i fully understand. The purpose of in taking and exhausting outside air is for co2 intake and heat exaust? Right? If you are supplementing co2 from a bottle or a pad or moonshine or whatever, and you have an air conditioner to control the temps/ humitity, why would you exaust air at all? Is there something i missed?? A 5000 btu air conditioner is only $100bucks at wallmart and 5000 btu is enough cooling for about 1500 watts of lights.
Lamp cooling (heat) and room ventilation (stink) I treat as two separate items. No reason to waste CO2 cooling the bulb.
I guess I dont see why you would want to ventilate the smell, especially if you have all of the other factors controlled separately. They you have to buy charcoal filters and hope they work. I would think it would be worse to have outside my house stinking like chronic than the inside. Also I wasn't proposing to cool with the co2, cool with the a/c. I was assuming that the purpose of fresh air was to replace the co2 that the plants used up and to cool the space. The co2 solves the co2 problem and the a/c solves the heat problem.
...the most efficient way to produce co2 is from burning propane or natural gas. ...an airtight room (without exaust) will create a breading ground for fungi quickly. Your plants only need co2 out of the atmosphere just as we like our oxygen but the humidity levels will climb quickly...you'll need a really good dehumidifier, and a very minimum amount of freash exchanged air, which require a constant production of co2 to maintain a 1500 ppm. One option many people go with is burning a sulpher burner. The sulpher lowers the pH of the grow area making it impossible for fungi to live. ...your objective is to maintain 1500 ppm of co2 in your grow area during daylight hours. ...in order to do this you need to have an airtight room with an a/c unit. I personally use the double hose portable ones to control odor and I aircool my lights to help out with temps. I have a monitor that maintains the level @ 1500 attached to a propane burning co2 generator. I have a carbon filter that is NOT exausted that runs constantly cleaning the same air over and over. A dehumidifier runs constantly. I have a very small hole at the bottom of my room that brings in new air everytime my a/c kicks on, this brings in new air because the a/c causes a negative pressure. ...co2 can be expensive, and if your going to do it right you can't be cheap about it.
That may be the case for those with large grow rooms but for those with small rooms bottled co2 is the only way to go. Propane will generate too much heat in a small space.
...they have aircooled co2 burners also, still an overkill for a small space, I agree...the op is talking about using an a/c unit, he must have a larger space.
I would run 20 lb cylinders until I made the leap to a full on controller and CO2 generator. 200cu ft is a "borderline" decision. I run cylinders but I am less then 100cu ft.
Until your running a large space co2 gens just dont make sense...my tanks last 10wks maintaining 1500 with lights on. I wouldnt even look at co2 gen unless I was growing in a much larger space the humidity/heat those put off would limit the size of application that I would use them. Numb
your dual hose a/c causes negative pressure? i have been trying to figure out if it does or not before i purchased one. If it's causing neg. pressur then it must be exhausting room air, which in turn exhausts the co2 enrichment... Right? But you run co2 with your a/c and you don't notice co2 being wasted? How long does your co2 tank last and how big is your tank?
You are right, use a CO2 tank to boost your CO2 to 1500 ppm. Use an AC to cool your space. You are good to go. I operate a very similar system in my grow and it is working great for me. Just stay focused on performance criteria, temps 75-80, CO2 @1500 ppm, keep your humidity below 40-50%. Means and methods are up to the individual and theior particular grow area, and especially their financial resources available for the grow Dont fuss about too many details, keep your eye on the performance criteria
I do notice co2 being "wasted"...but, that's how I do it with steller results. I use a co2 burner....which burns propane to produce co2. I only buy propane tanks, and one tank last about 3-4 weeks... "wasting" co2 and having new air exchange helps out with humidity .. and propane isn't that expensive......View my journal in my signature link to see the results.