Last year we suffered with too much CYA in our pool. This year it has been much better, and the water has been crystal all year. I just checked the CYA level and it has slipped below 30, to about 25. Is this ok? Why is the recommended level between 30-50? I have some stabilizer I can add if necessary. Thanks.

Where do you live?
Are you having a hard time keeping your FC level above the normal minimum for your pool and CYA level during the day or do you have to overdose FC above the normal maximum for your pool to maintain its normal minimum?
How are you testing?

If it is working for you, I am not sure I would add any. By working I mean, no algae outbreaks, need for preemptive shocking this year, no needing to add chlorine multiple times a day? You can post full test results if you want.

Any plans for a vacation in the near future? If so, you might want to wait until then to do anything. You would have the luxury of using trichlor pucks in a floater or automatic chlorinator for at least part of the time you were away.

I agree. If it's working for you, more power to ya. I ran at 25 last year without any issue. It was nice because it equaled out to 1 cup of bleach per ppm. This year at 40ppm CYA I have to add 2-3 oz to every cup to make 1ppm (depending on water level).

Thanks for the feedback. So I guess if it works, don't fix it. The water has been beautiful all year, and there is only a couple of weeks left in the swimming season here anyway. And yes, it is a good opportunity to use up a few of the pucks.