I have a 100gal. reef tank that has been going for about a year now.Some fish[clowns,scooter blenny,,spotted goby,chromis],leather mushroom,button polyps.My problem is I have what looks like this red carpet stuff forming in the tank.It tends to cover everything although it is most prevolent on the sand bottom. It siphons up in clumps but seems to come back rather quickly.What is it and how do I get rid of it?