Mmhmm. Very typical nuisance algaes to occur in freshly cycled tanks, their blooms seem to be tied to the availability of ammonia in the water column, or at the surface of substrate, in the tank.
Photos will help. If this is a new tank (1-2 months old or so) generally you just have to wait it out. You can minimize the appearance by siphoning it out, skimming heavily, and possibly doing water changes. But too many water changes will effect the pace of cycling. Its really best to deal with it if you hate the look of it, and wait it out.
When cyano and dinoflagellates pop up in more mature tanks we'd deal with them in another way. Let us know the age of the tank. And any inhabitants in the system.
>Sarah
