I'm running a cultured plenum, a UG and a sand bed in different tanks. Cyano has nothing to do with the plenum. Actually, I love the tank with the plenum in it! Its clean! And its loaded with life, fish, corals. Gotta love that. Its not that its perfect, but, you have to give a tank time for getting thru all the cycles and that takes a year at least. Algaes run on a seasonal-annual life cycle. The fuge can be a reason for little skimmate. Macro algae will consume the organics before the skimmer can get it.