I really don't know if I'm right or wrong on this problem but I have been dealing with red algae for a few months now. It shows up on some of my LR and on my substrate, usually 4 to 6 days after my last water change.
I've been using a two-fold method which has not eliminated the problem but seems to be keeping it under control. First, at every 10% water change (once per week) I blow the rocks and substrate off with a turkey baster, trying to capture as much of the red algae up as I go along. I also clean off the tank sides before I change the water. If you're careful, the red algae comes off in "sheets" and is easy to suck up with the baster.
Once a month during my real big clean, I stir the substrate, blow off the rocks and do a 25% water change.
I just broke through a hard, green algae bloom and I hope to get through this next bloom the same way, with regular water changes and lots of daily maintenance.
I've also, tryed brushing off the rocks with a soft toothbrush but I don't really like this method as much because it disburses too much debrise into the water.
Hope this helps.
Dianne =
------------------
You bought some rocks and they were how much?