So I'm tired of guessing to see if my CO2 is really working and is at optimum level, so I have decided to buy a drop checker. Problem is which one? I have been looking at this one for the past couple days, but I heard that these kinds aren't very accurate. Can somebody help me in this area? By the way, I use a 3 liter bottle of DIY yeast CO2 in a 30 gallon tank and I use a ladder to diffuse it with a powerhead above to break down the leftover bubbles. I am also thinking of adding another 2 liter bottle of yeast mixtoure to my tank.