Do not take this as critcism, well, distasteful or bad spirited anyway....Running c02 if not in a totally sealed recirc room, will only be truly beneficial once you have things dialed in. It seems like youre still figuring things out. I would suggest cutting off the c02 for now and get your room, strains and nutes dialed in, then add the c02 in and play with it. start pushing your plants a little at a time. C02 is only used by the plants during lights on, thats why people only run it then. Dont think its harmful at lights out but no need to waste it. Recirc setups need supplemental c02 as no fresh air is being brought in. The only thing the fresh air has that the plants need is c02. I assume most people in a setup like that are running ppm controllers with a photo sensor as it is very trick to do so without one.
I disagree with the way you suggest to dial in.
If you did it that way and added the Co2 later. Your likely to get some overfeeding problems. The Co2 increases growth by around 30+%. This increased growth is connected to the plant increasing everything it does to grow, by that same 30+%....
Dialing in is not just feeding! It's the total environmental package. Temps and RH control
is part of the dial in. If you gas or not.
Another thing to consider is that to properly have that Co2 working for you. You'll need to be running higher temps and higher RH during lights on....This is where an environmental controller comes in......AND a system that exhausts is needed! The idea of a totally sealed room and no air exchange, is not the best idea for gassing. The logic of sealed is better....is
not true.... Nelson's Greenhouse guide will reveal why, for Co2 generators, it's required the air be exchanged periodically.
Lastly. Just a heads up. While it's effective up to 1500 ppm. To actually get the plant to use that 1500 ppm, is basically next to impossible for the indoor lighted garden. We simply can't supply the amount of light needed to make 1500 ppm work.
The real upper limit or best effective ppm is 1300. Most who understand the laws of using Co2 will simply run at 1000 - 1200 ppm.
So will Co2 use at lower temps and RH work? Yes
but, no where near as effectively as if the temps and RH are controlled to use the higher available Co2 at it's best ability. Here is where that VPD chart should be followed.
At 1300 ppm, you should be running temps in the high 80's to 90 and match the RH to the VPD chart. Set your environmental controller to just above those values and gassing pays off much better then holding lower values, like when not gassing.
There is all sorts of confirmation of this in scholarly information across the net. Ed Rosenthal lines this out also..
Good luck.
