weird black dots attached to side of pool

[pamela]

weird black dots have attached themselves tothe side and bottom of our pool. they are teensy, but are clearly not dirt. they come off after vigourous scrubbing, but i'm worried bugs are breeding in the pool.
it is a salt water pool. any ideas.

[Larry]

It sounds like the dreaded black algae.

Black algae tends to be firm but comes off with rigorous brushing. If you don't brush, the top layer dies off but stays in place protecting the live algae colony beneath it.