Not sure what this is??

[ehb4PSU]

Does anyone have an idea of what this could be? Ive scrubbed it and it wont budge. Any help is appreciated.

 

[Oly]

Pool School......Pool School - Metals in the Water and Metal Stains

 

[Mendy48]

Do you have a test kit?

Also, view these links below!!!

Algae-Black Algae
Algae-Defeating Algae
Algae-Mustard Algae

 

[ehb4PSU]

Do you have a test kit?

Also, view these links below!!!

Algae-Black Algae
Algae-Defeating Algae
Algae-Mustard Algae

No, I ordered one and the reagents were about to expire so back they went. I had a separate post going where I was SLAM'ing for the first time. Happy to say the water went from green to clear blue over a week with consistent rain here in FL.
But now seeing your links makes me think we may not be done fighting algae?

I know the fight is now over with algae but I thought I had at least won this round.