Violet stains

[-fritz-]

I live in southern Nevada where it is extremely hot 5 months and the other months usually above freezing. We have been in the house for 2 years. Our pool is standard 16X20 volleyball pool about 16,000 gal. cap. About 2 months ago I noticed a violet colored stain just above the water line and about 4 inches above. I'm not doing anything different that I have been for most of the 2 years we've been here. I have always kept the chlorine a bit towards the high side and it doesn't irritate our skin, and we have no kids in the pool, ever. The pool was built in 1986 and is a bit "old style" but is in great condition with new pump and filtration, from about 5 years ago, I understand. Any ideas on why the violet color above the water line? The water is crystal clear and there are no other stains evident anywhere else. I tried scrubbing it off the tiles at that location, and it won't come off. It never gets worse, and if I put water in the pool to cover that high, it still doesn't go away.

[TSH Tech]

Hmmm, it's a bit of a rare pool problem, but purple/violet staining is due to Manganese in the pool. Make sure your pool chemicals are all dialed in, then treat the purple staining in the pool like you would with an excessive mineral problem.

[Guest]

Thanks. I'll give that a try. Although it seems like since the hot weather really hit, it seems like it's disappearing.

[chem geek]

You could also check your Cyanuric Acid (CYA) level and if it's high then the stain could be copper cyanurate if you've used either algaecide that had copper in it or Trichlor pucks/tabs with copper (some do). Copper cyanurate is amethyst in color. If the CYA is high (above 80 ppm) then a partial drain/refill will lower it. Metal sequestrants and stain removers can help with this stain as with manganese and other stains.

[lightandspace]

i think you have to change the tiles if it bothering you and not removing easily, the bacteria get stronger at the spot, i think just replace the part of it... lets check it out.