purple stuff on sand


Active Member
Do you have any pics of it? Cyano can cover everything in the tank if you let it. There are tons of threads about it here. It's also commonly referred to as Red Slime. There are chemicals that kill it off, but some safer ways are to try to physically get as much out of the tank as you can. Get some more water flow (powerheads), leave your lights off for a week (if you have no corals).
If you do decide to go the chemical route, follow the directions to a tee.