Following.
When my po4 gets stupid, and my nitrates are dumb. I still don't get cyano.
I use higher light than many, much longer as well and have a large coral bio load.
One sumped tank with fuge and One non sumped tank
I think flow has a lot to do with where it develops. Do you have a shallow tank with high flow? My 90G starfire is really tall and it tends to build on low-flow areas and on the sand first.