cyano problem

I am gonna do some research, but I thought I'd throw this out here to get some input. Some of our corals(elegance, lobo brain, candy cane) have started recedeing. The small polyps, frogspawn and mushrooms are all doing fine. Ammonia=0 Nitrite=0 Nitrate=0 Phospate=0 Magnesium=~1350 Calcium=~400...

i have been under a plauge of cyano bacteria for a while. when water is tested i double check it with my lfs and everything is good. cal and alk were high last time they checked but have done 2 WC since. i have 2korila 750's and 2korila nano 425's in the display with a hyperflow 12 return. now...