My tank is sadly becoming overrun with cyano, it's a carpet of red slime on the sand and is growing up the rock work. I've been told to use RO/DI, but I cant buy a unit as the house is not mine, and I know they need to be flushed if not used I wouldn't know where to start with one. I was thinking about getting a GFO/biopellet reactor? But which one would be best? I know I need to control Nitrates and Phosphates but which would do it best and which pellets are the best I've heard other talking about EcoBak?