Hello,

I am looking for suggestions regarding the cause for the discoloration appearing on my inground pool vinyl liner.

According to the test strips, the water in balanced. Unfortunatly the pictures are not showing it the best, but hopefully you can see the lighter spots (which are the color the liner SHOULD be) vs. the darker discoloration. The lighter spots are from where PH- dropped down the liner earlier in the summer. This is the third summer we have maintained the pool and we have never had an issue with this before. Our pool guy thinks the discoloration may be caused by minerals in the water, but suggested checking on here for additional opinions.

Thanks so much for your time and expertise!