looks like diatoms or brown algae to me.
Best fix... Otos hands down. Also if your bulbs are old then that may also be the issue. in the words of Tom Barr. "if you grow the plants, you wont have an algae problem"
I try to follow this. If i focus on growing the plants, ie providing enough co2, ferts, proper light cycle, then algae will disappear
-Just another day in paradise-