I feed Rods food once every other day and I only have one Koralia 1, I just purchased another one, that I hope will help. Parameters are good, so I'm hoping an increase in flow and a decrease in my photo period (currently 8 hours) will help.
I am nearing the end of a fight with cyano...it will not go away overnight...you can siphon it out with a turkey baster, and do more frequent water changes.
Did you test Phosphates?
More flow will help since it will not let waste accumulate. Rinsing food will help too.