Originally Posted by
LizStreithorst
You are one of the lucky ones, Vinnie. You can keep on doing as you have been. The reason the water changes pH after sitting with an air stone in it is that as the air bubbles it gasses off CO2 and the pH goes up. If it's surface water your working with it may contain too much O2. In that case the excess oxygen gasses off. Most tap waters come from a well and contain a lot of CO2.
Way back when I tested mine when I was new, my pH had just a .4 change. It went from 6.8 to 7.2. I thought that that wasn't a significant swing but after a month or 6 weeks I saw the Discus acting somewhat less happy. Not sick, but not happy. Once I started aging the fish went back to normal. Too many people don't know about this and it's a shame because it matters to Discus. These days I even age for my tanks that don't need it like my Rainbows, Bristle Nose, and shrimp.