I've tried them, but its related to your overall conditions. If for whatever reason you have limitations, light, ventilation, soil conditions e.t.c the CO2 tablets won't do that much, they don't work wonders unless your more or less spot on in all the other departments. I've heard from some people who have used them and had the same results and people who say they make a huge difference, gota try it yourself. I thought I would try them in the first place because you can't overdose.