I have a fiberglass inground pool. I keep having problems with some type of staining that starts at the waterline then goes down the sides of the pool. I have my water checked at my pool store and they have checked for all types of things. I have tried all stain removers but it keeps coming back. the only thing that removed it was a powder, but the staining still came back.i am dreading pool season as this is getting old. help.

Question:

I have a fiberglass inground pool. I keep having problems with some type of staining that starts at the waterline then goes down the sides of the pool. I have my water checked at my pool store and they have checked for all types of things. I have tried all stain removers but it keeps coming back. the only thing that removed it was a powder, but the staining still came back.i am dreading pool season as this is getting old. help.

Answer:

Knowing what color the stain is, what it looks like (spots, streaks, etc.) and where exactly it is starting and ending up (shallow end, deep end, close to inlet, far from inlet, etc.) would be helpful. Is it possible that it is starting in an area that is not getting circulated water (a dead spot) which is why it keeps coming back? If so, it may be as simple as adjusting the return jets. It may also be a biofilm that has not been properly scrubbed to break the membrane and expose it to the chemical treatments which would destroy it. For this reason, scrub first then add chemical treatment, then scrub again. There are other scenarios too, which is why the questions at the beginning are important.

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