pH of 7.8 has been the normal forever. It does raise very slightly with all the lights on. I have a pinpoint probe, and also test with a test kit occasionally. I used to freak out about it, but I have accepted it. I do run a calc reactor and run my lights in the sump opposite. Yesterday, with the cooler morning we had I was even able to let some fresh air in, but the highest it got was about 78.5 in the afternoon.