Stains versus Mustard

macgas

Active member
Jul 29, 2010
38
Houston,TX
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

TFP Expert
May 20, 2007
3,192
South Central NJ
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

TFP Expert
LifeTime Supporter
Feb 23, 2008
5,061
Denton, TX
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

Active member
Jul 29, 2010
38
Houston,TX
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

TFP Expert
LifeTime Supporter
In The Industry
May 20, 2007
12,177
SWSuburban Chicago, IL
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.
 

PoolGuyNJ

TFP Expert
May 20, 2007
3,192
South Central NJ
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
 
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