Cyano can be in fresh or saltwater. Most of the time the cause of it is where your getting your water. So even when you get rid of it you can still get it again later if it is the water your using. I have used chemiclean before and this stuff worked great for me. The algae died in 3 to 4 days and started to come off my rocks and sand so I sucked up as much as I could putting the water back in the tank to be able to keep sucking it out of the sand. Mine was really bad in a 125 gallon. but after all was gone I did a 50% water change and in 2 days it was back. So thats when I realized it was my water and I was a noob and didn't treat my water cause I was an idiot. So then I started buying my water from the LFS problem was gone forever.
Anyway I would try the Chemiclean or someone my chime in with a better option , cause I dont know 100% of nothing just a little about everything.