If you are not already you should start to use RO water. I was having a devil of a time with red slime. Switched to RO water, and after i got rid of the origial it has not come back. BUT it is really hard to get rid of. I used a product called erase and it worked really well. It kills off some of the other algae too, but it gets rid of the slime.
Good luck
it is red slime but not to worry you can clean it up with a partial water change, use phosegaurd and also a tablet of maracyn (freshwater), it is reef safe and invert safe as well add 1 tablet once a week for 3 weeks.... then do another water change, and be sure to have a good filtration system, and water flow.... watch the over feedings!!!! good luck