Opps, I lied (well, forgot actually) I added DE to my sand filter this week as it has been suggested on a thread else where that this will "polish" the water (did I mention the sparkling water obsession?). But the ph thing was happening before that, so I don't think that's it.
The CH is 110 (again I think this is in the acceptable range - though I have a vinyl pool, and no heater, so it shouldn't matter).
I did recheck the TA and now it is 80! Would adding the DE affect the TA? I had checked the TA several times since opening in May and it had alway been 100-110 so this is new.
I have no water feature so the only aeration option I have is turning the return nozzle to the surface (would that help?). I've seen add on fountains (seems to hook into the return) at the pool store - do I need an excuse for a new pool toy?
Thanks for all your suggestions