We have had our pool for 7 years now. Never had any problems. We are very low maintenance, we just added salt every once in awhile and it was always beautiful. I don't think we have ever even tested the water, til this year. After getting it ready for the season we noticed the water was sparkling but the liner and steps were yellow. So I did the only thing I could think of and went to the pool store. Yikes! $400 later, pool looks fabulous again! Yay, money well spent. It looked fabulous for 2 days, then it turned cloudy, shocked it, then noticed stains...again. Back to the pool store, another $150, stains still there. HELP!