Major Catastrophe, Need Help

HI
Just had a major disaster with my reef tank. I was out of the country
for 7 weeks and the person that was supposed to take care of the tank
didn't.
When I returned home, the sump pumps had stopped and the tank was
loaded with red algae which also is covering all the live rock, quit
thick, about 100 pounds worth as well as the glass. All the coral died
as well as the few fish, crabs and snails I had in there. There are a
few small starfish around yet.
My question is, how can I get rid of the red algae on the rocks
without destroying any of the life in the rocks.I do want to set it up
again when I move in a few months.
Thanks