Rust stains on the bottom of pool


LifeTime Supporter
Aug 19, 2013
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


Mod Squad
TFP Expert
Platinum Supporter
LifeTime Supporter
In The Industry
Apr 1, 2007
Sebring, Florida
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.