Chris, how much salt have you had to add this summer? - I tie the salt and cya together, when I add 1 I add the other (only exception is a tri-chlor pool getting a new SWCG) The ratio I've worked out is 1 lb cya/ 100 lbs salt to get to 30- 40 ppm cya with ~ 3000 ppm salt, so far it hasn't failed me to keep the cya at the level I want (one exception - the pool owner was removing the 'packets' of cya I was putting in the pool and therefore having a constantly low cl reading), if you want the 60 - 80 ppm cya reading, simply add 1 lb cya for every 50 lbs salt. Neither of them will evaporate, so where the salt goes so does the cya -- they only leave by emptying the pool or splashout - if your unit tells you the salt level and you need too add more salt, add the appropriate amount of cya

Unfortunately, cya doesn't have a comparable product in the grocery store , it's a pool specialty product. You may still be able to find some at Wal-Mart, Home Depot, Lowe's or similar - it may even be on sale if they still have it this late in the season.

I hope that this at least partially answers your question, and once you get this fixed you have the same 'lack of problems' that you've enjoyed most of the season!