Stains versus Mustard

[macgas]

My pool is crystal clear and the overnight FC does not change. All drop test are normal except CH is 360

In the deep end I see a couple of spots that are brownish/yellow. These spots do not change when I brush them with a wire brush and do not appear to be growing or changing.

How do I differentiate between stains or MA? If stained how do I get rid of them?

 

[PoolGuyNJ]

MA would brush off.

A complete test results is needed. Your hardness level is a bit on the high side and if the pH and/or Alk levels are too high, scale will form.

Scott

 

[257WbyMag]

Agree with PoolGuyNJ in that we need to see the test numbers.

Are the spots in question raised? Any chance that they could be metal stains?

 

[macgas]

OK here are the results. FC 7.5 put in 2 quarts at 4pm. CC 0.5 pH 7.5 T/A 130 CH 320 CYA 50 Temp 91 degrees

The spots don't appear to be raised. I haven't used any copper based algaecides but I am not aware of metal in my water but I guess they could be metal. How can I tell?

 

[frustratedpoolmom]

Hold a Vitamin C Tablet on the stains. If they are iron, they will fade rather quickly. If they are copper, they may change in appearance or darken...

A trichlor tablet held on the stain, if it fades, would mean the staining is organic.

 

[macgas]

These spots are in the deep end. How long do I hold the different substances to the spot?

 

[frustratedpoolmom]

Vitamin C will work almost immediately if its iron. The others could take longer. You may have to try to figure out a way to hold the tablets on the spots...

 

[PoolGuyNJ]

Crush the tabs, put the powder in a nylon sock with a rock in with it to hold it down.

Added:

I suspect scale though. If nothing happens with either the Vit. C or trichlor tab, it's a good bet.

If you could post a pic...

Scott