Stain on bottom of pool

Apr 29, 2017
San Antonio, TX
Hi all,

New pool owner here and I'm having trouble with some stains on the bottom of my pool. I've scrubbed and scrubbed and it won't budge. I've got everything balanced now so wondering what I can do to get rid of them. Picture below.

Prime Photos

Any ideas on what it is and how to clean up?



Mod Squad
TFP Expert
Platinum Supporter
LifeTime Supporter
Aug 10, 2012
Welcome to TFP!

Are there IMG codes in google? You can paste them into the forum and the pics will show up in the forum so people don't have to click out to find the forum to see the pics.

More here about pool stains, Pool School - Pool Stains


TFP Expert
LifeTime Supporter
Jan 6, 2010
San Dimas, CA (LA County)
That's Calcium scale that has been tinted by metals and/or algae.

It won't lift easily or quickly. It can be dissolved by keeping the CSI slightly negative and brushing with a steel brush, but think glacially in terms of speed.

If you want it gone this year, you're looking at an acid wash or sandblasting.


Mod Squad
TFP Expert
Platinum Supporter
LifeTime Supporter
In The Industry
Apr 1, 2007
Sebring, Florida
+1 what 320 said.....both in terms of identification and solution.

My thinking is you have lived with it for some time so trying the slow approach (months) to getting rid of it might be your best bet.