Upgraded your membership.

You are welcome to read the stain-removal guides here. Obviously, I have some ideas about how SOMEONE can "safely remove the unsightly stains". Unfortunately, about a decade of experience suggests that while I can remove stains using those methods, you can not, if you are like about 99% of the other users at PoolForum.

Worse, fiberglass stains are something of a special case.

If you want useful help, you'll need to do all of the following:
  • Get a K2006 testkit (or the TFP copy of my old PS235)
  • Test BOTH your pool water AND your fill water.
  • Take good photos of the stains and post them to Google Photos or some other service you can link to.
  • Post ALL the info -- pool photos AND test results -- here and to TroubleFreePools

Look for responses that start, "I had stains like that, and I did X". (That's why good photos are so important!) You can probably ignore all the other responses and especially those that begin "If you do Y, it might work . . ."

BUT, the reason most stain removal fails is that removing them is one thing; managing the problems that CAUSED them is something else. Lots of people succeed in removing them briefly.

Good luck!