Added CyA little brown spots on pool floor.

[smallpooldad]

Adding 16 oz CyA little brown spots formed on the pool floor (in-ground plaster), intermittently dispersed. The pool cleaner was going but had not yet hit that area, so I sucked the CyA up into the filter afterwards there were little brown spots left. I then removed them with a wire brush. But what were they?

Standard Pool specs are as follows:

Measured pH 7.5
Total Alkalinity (ppm CaCO3) 70
Free Chlorine (ppm Cl2) 4.0
Cyanuric Acid (ppm CYA) 30
Calcium Hardness (ppm CaCO3) 500
Total Dissolved Solids (ppm) 3,620
Total Sulfate (ppm SO42-) 0
Total Borate (ppm Boron) 50.0
Total Ammonia (ppm Nitrogen) 0.0
U.S. Gallons 10,000
Temperature (oF) 83

Total Chloride (ppm NaCl) 3212
Carbonate Alkalinity (ppm CaCO3) 53.7
Langelier Saturation Index (LSI) -0.05
% HOCl (vs. Total Free Chlorine) 1.5%
OCl- (as ppm Cl2) 0.072
HOCl (as ppm Cl2) 0.058
Calcite Saturation Level (CSL) 0.66
Calcite Saturation Index (CSI) -0.18

 

[spishex]

So if you ever have to add CYA again, go ahead and do it through the skimmer. Takes the stuff too long to dissolve in to leave it on the floor anyway.

Not sure what the reaction would have been. Were you adding any other chemicals at the same time?

 

[smallpooldad]

Spishex,

Thank you for responding.

Good idea I will add it through the skimmer. I had added some salt, as I had drained down some; that might be it.

Aloha.