Is it ok to pressure wash my Holey rocks they have become covered with green algae? I would think that I have enough good bacteria built up in my filters to be able to get rid of some on the rocks.

a power washer is going to be pretty aggressive if the rock is a soft stone like sandstone you could litterally blow it apart - -depending on its size i would simply boil it in some distilled water. i have hair algae on my rocks in a salt tank and i put the rock in another tank with high sality water with a bubble disk and in a couple weeks the algae dies off and then it gets recured in regular salt water and back in the tank.

but for a freshwater tank, i think you could just boil it and scrub with a tooth brush

lol dont put the rock right back in the tank at 200 + degrees...........fishies might not care for that .....hahahaha