Spots on floor of pool. What causes this and how do I get rid of them ? I am a new pool owner.

Texas Splash

Mod Squad
TFP Expert
LifeTime Supporter
Hello and welcome to the forum! :wave: Those are some interesting circular spots. Any UFOs in the area? :) Okay, let's start with the following:
1 - Update your signature with all of your pool and equipment info (see mine as an example). Appears to be plaster, but all info will help.
2 - How do you test your water?
3 - Can you post a full set of water results? (From TF-100 or Taylor K-2006)
4 - How do you chlorinate?
5 - Pool history? New, or existing home purchase? Anything else?
6 - Any autmoated cleaners used?

That should help us get started.


Dec 12, 2018
Coral Springs
I use the TF-100 Pool test kit.
it is a Chlorine pool.
It was an existing pool with home purchase
I use a suction side cleaner We named him Flash after the Sloth in Zootopia

i will be testing the water this afternoon.

Texas Splash

Mod Squad
TFP Expert
LifeTime Supporter
Spots of that particular pattern are not reminescent of typical organic or metal staining unless something round like that rested on the floor's surface for a while. I don't see how the cleaner could contribute to those. I have suspicions about the base underneath. Your water tests later might help. I'll ping the assistance of others to see what they think. @JamesW


TFP Expert
Mar 2, 2011
The spots are too perfect to be a chemistry issue.

I suspect that someone probably threw tabs in the pool.

I suspect that it probably wasn't the previous homeowner, but someone responsible for the house between owners.

Was the house unoccupied for a while?