Brown spots/streaks on floor of agp

[Jscottwoodwork]

Hello

I opened my pool about a week ago. Balanced chemicals /added Borax to up low ph. Shocked with liquid.
A few days ago I noticed a few brown spots or streaks that are lying in crevices or low spots of floor. No spots on wall. Water crystal clear. I figured maybe it was sand from the pool stair weights. I hooked up the automatic robot cleaner with filter. It removed all the spots and I thought all was good. 1 day later they returned. Vacuumed again with robot x 2. A day later they are coming back.

Is this an algae? A mineral copper/iron?

Please advise! Thank you!

PH - 7.5
TA - 110
TCL - 10
FC - 10
Hardness - 160

 

[duraleigh]

Welcome to the forum

Is this an algae?

Almost surely that is dead algae. You will need to SLAM the pool but it will be a short SLAM.

Please read the SLAM article in pool school and then ask lot's of questions. We'll all help make that stuff disappear permanently

 

[Jscottwoodwork]

Thanks Dave!