Purple slime

[tbone]

how old is your tank?
if it's a new tank then it's going thur it's cycle.
first you'll get your cyano bloom (red algae)
then your hair algae will start.
do you have any fish in there?

don't over feed your tank.
what kinda of lighting do you have on your tank?

cut down the lighting duration.

water changes is always a good ideal as well.