I'm hoping someone will have some good ideas for me. I've got a 26k gal IG gunnite/plaster pool with the majority of volume in the "deep end", pool ranges from about 4ft to 8.5ft in depth. I bought the house about 6 years ago and the chemicals were all a mess--the CYA level was so high there was no effective sanitizing. A year after owning I completely drained and acid washed the pool. Unfortunately the kid at the pool store refused to test my water until I added stabilizer to the pool--in hindsight I never should of done that as it apparently collects in the plaster (original since about 1992) and leaches out as I later learned. Anyway long story short, now its about 5 years hence and I've got CYA levels so high I can't test them with my test kit--maybe 175-200+ range (don't know if it's a linear scale on the measurer) calcium hardness is over 1000 and I can't sanitize the pool effectively.
I'm not really sure how to proceed, I'm in Dallas, TX and I don't know what our water table is like, but I'm paranoid about re-draining the pool and possibly causing a disaster. At the same time, I can't shock the pool to 96ppm which is the mustard algae shock value for that level of CYA...nor can I keep the sanitizer high enough to be effective.
Pool guy is coming tomorrow for the annual DE filter maintenance, but they don't do the chem--I do. I'm probably going to tell him not to recharge the filter once he takes it apart and cleans/puts back together in case I've got to do some kind of draining.