I have a 55 gallon planted tank, also running pressurized co2 at about 5 to 7 bps, and am also using the pps-pro fertilizing method. My question is concerning the co2 levels. I have hard water. GH about 13 and KH about 11, ph is always at around 7.4. If adding co2 is supposed to lower my ph a bit then why does my ph never change. I think it's because I have such hard water and the kh is high therefore to bring the ph down with co2 alone I would have to pump lots of co2 into the tank. I am however not trying to change the ph at all. What I was wondering is will simply putting co2 in the water and not knowing if the plants are benefiting from this or not. I think I am just wasting the co2. Maybe I can get away with less bps as there is now way for me to check the co2 level accurately enough. Using the kh/ph method always gives me the same result as to my co2 levels which are very low. As for the plants to get enough co2 and not changing the ph or the color of the dropchecker are concerned what do I do. Reduce the bps. The plants look good and yes I know that if they look good then things must be working. I guess I could reduce the bps count and see what happens. Oh I do have green hair algae that I have been trying to get rid of. Maybe adding some missing ferts will help. So the questions are not tank parameters or plant types of fish load or lighting or anything else. Just if you think I'm wasting the co2 when I can't or don't want to change the ph or kh (which is hard to do anyway and would hurt the fish trying to change things all the time).