take cyano as nature's way of telling you something is not right with your tank. the most common problem is not enough flow! you want to aim for 15x your tank in turn over from your main pump.
so double check your GPH's and make sure to include vertical height in your calculations, it makes all the difference.
that is your first thing you must check, but in the mean time, reduce the photo period, suction out what you can physically when you are doing the WC's, and check your levels. and reduce food to scarce rations
*** also, i want to add, it is always best to take these oppurtunites to fix the problem with your tank as opposed to masking it by trying to remedy the symptom with some chemical additive. if you can avoiud dosing your tank with chemicals, do it!