Yellow Stain appeared

[MrcTag]

Hi everyone and thanks for all the great advice,

I recently had a pink algae problem and had a hard time getting rid of it, I shocked the pool and it disappeared but came right back so i went to the pool store and bought some "Pink Treat" from united chemistry and followed it up with 2 lbs of Trichlor. This took care of the pink algae but now I have a yellow stain in my spa that won't brush off. Does anyone have any idea how this came about and what treatment I should use to get rid of it? Any help would be appreciated.

FC = 2
PH = 7.4
CYA = 130
TA = 116
Hardness = 248
salt = 3300

22k inground plaster pool with spa and chlorine generator

 

[JohnT]

Have you tested for metals in the water? Sometimes shocking can cause metals in the water to stain the pool surface.

 

[MrcTag]

Thaks for the quick response John,

Yes we had the water checked for copper and iron and found none.

 

[JasonLion]

With a CYA level of 130 you need to keep your FC at 10 or higher to keep algae away. Your current FC level of 2 isn't nearly enough. CYA levels that high tend to cause complications, such as the pink algae problem you just had. It would be best if you could bring your CYA level down dramatically by replacing water. Using trichlor or dichlor will just make it worse, as they contain CYA.

You can narrow down what might be causing the stain by rubbing it with a sock containing a couple of crushed vitamin C tablets and see if that has any effect. Then try gently rubbing it with a trichlor tablet and see if that has any effect. If the vitamin C removes the stain then it is probably iron. If the trichlor removes the stain then it is organic and shocking the pool (which will be difficult with CYA that high) will remove the entire stain. If neither works there are other things to try.

 

[MrcTag]

I just went out and tried both treatments you suggested and it didn't seem to have any effect. Could my high CYA levels be hampering my attempts at cleaning off this stain?