Switched after finding this site. No complaints but have a question relating to getting the CC in line. Dichlor obviously is effective to stabilize when shocking but it adds to CYA which everyone here says is not good (once above 50). So I refilled 80% - 90% of a 365 gal capacity hot tub and started over - getting CYA controlled then switching to 6% unscented bleach. As part of the cycle CC rises so I shocked with bleach using the calculator as a limit. Attached is the spa log where I did this 3 consecutive days (end of DEC) with no real reduction in CC value. Then learned about MPS - so bought some and followed directions. Used weekly along with bleach since MPS is not a sanitizer (set the FC target during MPS shock at around eight). For a month, I still haven't been able to show a real significant CC drop (I believe target is <.5 or so).