Black algae or metal stain

[Watermom]

Look at the bright side ---- you will build up your muscles brushing!

[PoolDoc]

Keep in mind, we haven't established that any of those spots ARE black algae. The most definitive test is to scrape some off with your fingernail, and smear it on a white card: black algae will smear dark green.

Brushing will make plaster wear through spots WORSE!

But, if you DO have black algae, a brush like this

Pentair R111616 604A Algae Brush with SS Bristles, 6-Inch

will help.



NOTE TO OTHER READERS: Do *NOT* use a metal bristle brush on fiberglass or vinyl pools, EVER!