OKay got cyano now what?

[findingnemo1]

HI there.

First post and what a crappy way to start off. I have cyano covering my sand. Not on the rocks just a nice pretty blanket on the sand. Have been sucking it out daily and have done 3 20 percent water changes for the last 3 days. Nitrates are at 30 and everything else is 0. Salinity is 1.026, calcium is 400 and dkh is 10.
No sponges to trap the nitrates and the skimmer is going. This is a 130 gallon system. I saw poly ox i believe at a store the toher night but am a little hesitant on putting anything un naturral in the tank. So what am i to do? Everything is thriving and healthy it is just this really ugly stuff ruining my sand.
Oh yes iand i am running rowaphos in a reactor. The rowaphos is only a week old.
Any suggestions would be welcomed.

C&L