First I'd like to say hello to everyone, and I'm really excited I found this site (I'll be ordering a TF100 test kit soon). Last fall we finally bought a house with a pool and have been looking at it every day since, just waiting for it to be warm enough to actually enjoy. The pool was built in the 80's and replastered about 6 years ago. We've been having the water test off and on the last few months at the local pool store chain. A few months ago they said our CYA was over 100 and we needed to drain about 1/3 of our water out and replace. We did this and CYA reading came down to around 90. After having another test done yesturday we were told CYA was to high again and that we needed to do another drain and fill, but as we drain the water we should brush the sides with a solution of 1 part muratic acid to 2 parts water, and that since we hadn't done this the first time, that is why our levels are high again so soon. So here are my questions:
1. Should I do the acid scrub/brushing on the pool walls as I drain?
2. I've read mixed reports that the cya tends to float to the top or sink to the bottom. Which is true? The reason I'm curious is it seems where it sits in the water would be the best place to drain from, so if it sinks, using the main would work best, if it floats, then renting a sump pump and placing it on the stairs might be the better option. Am I over thinking this?
Any help is much appreciated.