I am in the process of closing my pool and would like to get rid of the stain. The stain is light brown and along the bottom perimeter of the pool. The stain has been there for a while, I also had iron stain problem which was resolved with ascorbic acid treatment, but the light brown stain is still there. So I am assuming the stain is organic. In preparing for the season closing, I've shut off the pump and plugged all the returns. I am shocking the pool and have increased the FC to above 20, all my readings were normal prior to closing, CYA was about 40. It's been about 5 days, I was able to maintain the FC day and night without having to add too much chlorine. I have an automatic pool cover so the pool is covered almost all the time, I tried to brush the stain twice a day. So far the stains are still there. Should I continue my shocking and brushing regime? Will the high FC damage the underside of the pool cover since it is in contact with water?
Need help with light brown stain in fiberglass pool
- Thread starter Ke
- Start date
It could also be calcium scaling. Can you feel any roughness on the surface that is stained?
The water is too cold to go in, but that part of the pool surface has a "grainy" finish and that is where the stains begin, the pool wall has a smooth finish so there is no stain. So even if I can get down there it will be difficult to feel for roughness.
Back to my question, do you think the high FC will damage the underside of my pool cover?
Back to my question, do you think the high FC will damage the underside of my pool cover?
It is possible for very high FC levels to damage pool covers, but it is fairly unusual. Pool cover damage usually only happens when you spill full strength bleach directly on the cover. Pool covers almost always fail for other reasons well before enough damage from chlorine builds up to make any difference.
