Originally Posted by Dugsul808
Could it be brown algae?
It's easy to wipe away but It came back in a 2 days
It's possible. Typically diatoms wipe away easily, brown algae does not. Diatoms are prevalent in new setups. Diatoms also grow quickly. Everything seems to point to diatoms. Ever hear the phrase, if it walks like a duck and quacks like a duck, it's a duck.