Rust stains on the bottom of pool

[dkbrat]

I noticed a few rust stains a few months back. I thought my husband sprayed some fertilizer pellets in the pool. The spots look about a 1/4 inch in diameter. Now I notice more closer to the main drain, and we have not spread any fertilizer. I have tried brushing, but this did not help. Any thoughts what this could be

Test results today
FC 3.4
CC 0
PH 7.8
TA 70
CH 270
CYA 50
Borates 50

I have been using 10% bleach in case this has any impact

 

[duraleigh]

Thanks for posting your test results.

I think my first step would be to positively identify the stains as iron. Do you know to crush up vitamin C tabs, put them in a sock and then sink it down to be placed directly on the stain for five minutes or so. If the stain comes off or is very noticeably removed, it is an iron stain.

 

[dkbrat]

Thanks, I will try that.

 

[Richard320]

I put a bunch of Vitamin C in a knee-high stocking with some clean river rocks and tied a string to it, then tossed it in. It's easy to shove it around with the brush and fish it out later.