There's alot of folks who use "alternative sanitizers" and brag about water that's years old blah blah blah but as you stated, there's nothing like fresh water, nothing. I find very little info on CYA except I heard of one guy who tackles the problem by using triclor every other time to keep it lower. Not sure about that idea but it seems theres very little available regarding how to reduce it. The MPS and dichlor thing we both do seems to help also, but dichlor as a shock or sanitizer is far superior to MPS. Soak relax and ponder the CYA