Not sure about using CO2 I'm afraid. Hopefully someone does.
I am a new grower but I can tell you that I have tried multiple CO2 solutions and would advise you save your money on those CO2 bags (Exhale). I say this from practical experience, not opinion.
There are a lot of variables when talking about this topic so the best way to confirm is to do your own testing. I read tons of reviews (for many different solutions) that talked about how great they work; some with ppm values that seemed to validate their review so I bought in and gave them a try.
Like I said earlier, I tried mushroom bags, sugar/yeast buckets, folic acid/sodium bicarbonate buckets and I was very disappointed in every one.
I fell upon this thread randomly and did not read it from the beginning so forgive me if I missed something on earlier pages. Before you go after CO2, you should have all of your other parameters dialed in first and have a high light intensity light to utilize the enhancement.
Also, you need a decent quality CO2 meter so you can feel confident with the data. If you are there, I will share my experience with CO2.
I started with a large Exhale bag in my small 3x3 tent. I do circulate my air into a small 10x5 lung room which is reasonably sealed. My CO2 levels were awful (I gave it the benefit of the doubt because they do need time to fully activate so I stayed with it and continued to get terrible results. I added a second XL bag to see if maybe I had a bad bag but nope, barely moved the needle...
I tried most of the common DIY solutions and all of them are insufficient. My research suggests your two main (effective) options are 1) a CO2 bottle, regulator and controller or 2) a propane driven solution which are very effective but will induce heat and most growers are constantly battling temperatures so if you are like me (in a very small area where additional heat is a deal- breaker, this can require some special solutions).
I went down the rabbit hole trying to come up with an out-of- the-box solution and by the time I got everything working properly, I wished I had just went with option #1 above. I was trying to save money and live in a rural town where filling CO2 bottles is inconvenient so I was willing to try anything but by the time I was done getting everything to actually work effectively, I spent approximately the same and felt like I could have used all the time/ energy doing better things.
If you are going to enhance, do your research and make some calculations for the long term as it is easy to waste time, money, or get lost like I did. I didn't really have any guidance and wish I could have relied on the reviews you see on the internet; in my case they were wrong.
I wish you luck with your grow and will be watching...
