Carl,
Reading between the lines, I'm guessing that Tri-chlor has the side effect of lowering your ph.........
or does acid rain, normal life do this. I ask because i do not think i've ever had to lower my ph, but I do need to bring it up using 20 mule team borax every so often.
I just added some today because my ph was 7.2...although I won't even "open" my pool and hook up my filter for a few weeks.

Thanks,
Frank D.