Cyano feeds off of phosphates, nitrAtes, low oxygen, and red spectrum lighting. So, add phosban; use ro/di water, keep up with your water changes, make sure you have good flow to reduce stagnant areas, and be sure to replace your florescent bulbs every 8 mo.
In the interim, physically remove as much as you can. In doing so, you not only remove the unsightly algae, but you also are exporting the nutrients that it has absorbed.