Oh, the lighting thing might be the issue, I had only my actinic on for a few days so maybe that was the reason. I will keep checking to see if it stays normal now. I'm not sure if I have the appropriate amount of circulation either but I have had the same setup for awhile and only recently started having the Ph problem.
I have a 180 with a mag 24 as the return coming in on both sides of the tank and then 4 maxi jets 1200 hooked to a wavemaster