can't get rid of this, help!!

[schippy]

I have my tank up and running for some time now. I have this brown algea that grows on the rocks and the sand. Never the tank. I suck it off when i do my water changes but seems to come back. It forms clumps on the sand and easily scrapes of the rock. I have tried keeping my lights on less and feeding less. notheing seems to help. I use RO water so that ids not it. any suggestions?

 

[balashark21]

what is your cleanup crew like????

 

[blk822]

If it's red it may be a red slime....actually a bacteria

 

[schippy]

it's brown and i have a large cleanup crew

 

[nicky1.8t]

weird doesnt lawnmower blennys eat that stuff?