Thanks for your help. I have pearling, and so far the fish seem ok. I was having trouble with that chart based on the same reason you were saying. It could just be useless. For example what if I'm not adding any CO2...I would still have a KH and PH reading that could say that I have ??ppm. I'm going to go with eyeballing for now. I'm starting with 2 bubbles per second.