I hooked up a diy co2 system to an airstone and put it in the bottom corner of my tank and had lots of little bubbles coming off of my plants and my Fluval co2 indicator said i was right in the green where i needed to be. Then i might have over read on something that might have been working. I found out airstones are no good and that I would have to get a diffuser. So I ordered one (inexpensive fluval diffuser from amazon) while I was waiting for it to get here I started to read where it would likely not work with DIY plastic jugs and yeast sugar mix. Not enough pressure. While I used a thick juice type jug and a gatoraid bottle and took my time drilling under sized holes in the caps - sanded the holes down, pulled the airline thru the holes the only possible way, with pliers as it was a really tight fit and syliconed the tops and bottoms of caps. Long story short - the system dosen't leak and the diffuser works really good at sending out a real even group of bubbles all around the cermic disc and works just like it's supposed to However, my co2 indicator will not turn from blue to green the area where it supposed to be for the proper amount of co2 - it's registering and not enough co2. Should i go back to my airstone that gave good indicator readings and a lot of nice plant growth or just stay with the ceramic disc diffuser and be patient???