Quote Originally Posted by swimnfun View Post
I have a 16x32 inground vinyl pool. I have been unable to get my chlorine levels down in over a month and realize that this is due to the CYA levels from having used Trichlor tablet over the years.

I don't know if this makes a difference but the building is "see through" and has doors that open at the side. We have had little sun here in North Idaho so have had the building closed.
+ Do NOT use trichlor on an indoor pool. Do NOT use dichlor on an indoor pool with CYA > 50 ppm.

+ If you use cal hypo on an indoor pool, you MUST learn to how to *SAFELY* add it to the skimmer, or you will have other problems.

+ If your pool and equipment is salt-compatible, that would probably be easiest.

+ Bleach will be next easiest. Cal hypo will work well, but ONLY with a sand filter, and ONLY if you learn how. Following the label on the bucket will NOT work well, long term.

+ Do NOT worry about 1 ppm CC levels on an indoor pool. If anyone swims in the pool, you probably won't get lower. What will lower the CC levels is direct sun (or a UV system!). Combined chlorine compounds that appear in indoor pools are usually NOT the simple chlorine + ammonia compounds described in the pool industry literature.

+ As rule, it is NOT safe to drain vinyl inground pools. It sounds like you've dodged that bullet, but if you drain too much, you'll lose the liner.