Thank you for replying Carl. My liner is vinal.

I thought that you must keep the chlorine at or below 5ppm?

I had a terrible algae issue last year (pea soup). We went on vacation for a week and my filter shut off. I had to add so much chlorine I thought I would bleach my liner. I drained 1/3 of the water at the end of the season. So there is no way to reduce CYA other than draining?

Do I use standard pool chemicals to lower the alk?

Best regards!!!