I bought a 20' Intext Ultra Frame last summer. We have a salt system. We winterized and uncovered a crystal clear pool in the Spring.

My numbers have NEVER been right. All the tests I have used indicate that I have NO chlorine in the pool. They indicate that everything is low.

The water remains crystal clear. I change filters frequently.

There is a large brown stain on the bottom, really only visible as the day moves into evening. It does not scrub off and it is not slimey.

I ran my system for nearly 24 hours to see if that made a difference. It still showed no chlorine, BUT it turned my son's swimming trunks green.

I have no idea what to do...