I really appreciate this forum and the pool calculatory. As a former chemistry major it was extremely intuitive to me.
My troubles with my pool begin when I purchased our home 2.5 years ago. The pool was freshly replastered that year (2010) and winterized. I opened it to a high pH and some moderate scaling around the floor returns on the pool. I figured this was due to improper pool maintenance or issues with the new plaster. I found the BBB and installed a SWG that year and had an event-free summer. I opened the pool again last year with an off-the-charts high pH (despite closing it with it being around 7.5) but didn't notice any extensive scaling. In retrospect this was probably because I was not getting a particularly accurate CH estimate (either had a bum reagent or an expired test from my TF-100 kit) which was probably around 200.
So long story short, I close the pool with the following numbers: pH 7.5, TA 60, CH 300, CYA 70. I open it again this year with a pH off the charts (at least 8.2) and further extensive scaling seems to have developed, mostly as a "ring" around the bottom of the pool (very similar to how a shower tub develops a ring). My current numbers otherwise suggest good closing chemistry (TA 60, CYA 40, CH 200) so I can't figure out what's happening. So my two major questions are:
1) What are my options for scaling mitigation? I am aware of acid washing and the no drain compounds. Any strong opinions or success stories about either? What is a reasonable price to have a 20k gallon pool acid washed?
2) What in the world can I do to prevent this pH creep over the winter? Why is this happening? I suspect there was a material used in the plastering that was probably not appropriate for a pool that's winterized. Otherwise my MA requirement is not awful during the year (~1-2 cups per week of MA).
Thanks for all of your help and again appreciate this forum.