black(charcoal) stains

[cwos]

I have a new pool with a starting alk of 450ppm( holy thats what I said but had it checked over and over) any way after a week of adding acid I am noiw in the 200 range still high but this is taking alot of acid!!! and the water has cleared greatly but I am noticing blackish stains developing in the deep end walls and not able to scrub off.Whats happening and how do you make these go away!!!!!!!PS ph is staying about 7.2-7-4.

[elvinp]

Did you ever find a solution to this problem? I am having ht e same issues and no one can figure it out.

Thanks

[makajo]

i have same issue, what is it?

[Buggsw]

Sounds like metal in the water.

Have your water tested for metal. Could be copper or iron.