Mustard Algae - Description ?

[haze_1956]

Thanks John,

Could you tell me if it was in small patches or a large continuous area ?
.

[JohnInSoCal]

it was mainly in patches. If I let it go long without brushing then it would continue to spread. I have a grotto with a bench and it would grow on that bench, on a step near the beach entry, on the walls in the shade and on a wall in the spa.