hmmm thats kinda werid you had a sudden outburst of algae, I'm not sure why that happened. do you have any algae eating fish? Otos are miracle workers when It comes to eating algae, you could try a couple of those. Or browse your local fish store there are hudreds of new gadgets to remove algae, try some of them and see what works the best! Good luck with your algae problem *twirlysmiley*