Hi Fishlore, I was testing tap ph before water change today and I'm getting 6.4 on the regular API ph test, 8.4 on the high range test. Lately in has been right around 7.4-7.8 so I was using both tests to be sure. My tank water is what I expect: low range ph reads dark blue 7.6, high range 8.0 (this is about normal for my tank). So I'm holding off on my water change b/c I don't know if the tap ph is really 6.4 or 8.4. I tested several times. I don't get it. And what the heck am I going to do if it's really 6.4? Our poor fishies will be shocked. My tap ph is usually on the high side. We had recent flooding in central texas and I know they've been struggling with treating the water. Maybe that's affecting the ph. Any ideas? Thanks !