In my experience - cyano is light sensitive. It looks much better when the lights first come on in the morning (maybe even gone) and gets progressively uglier as the day goes on.
Also cyano will blow off the sand bed in "sheets" where as diatoms are dusty and won't come off in sheets but will blow off in a cloud. Diatoms also "dust" everywhere - its on the glass, rock, sand - everywhere where the current will let it settle.
I think some may be confusing diatoms with dinoflaggellets (dino) which often appears in conjunction with cyano and forms little bubbles in the mats.
Color doesn't mean too much with cyano - it comes in an assortment of colors from red to bright green. Diatoms are always a powdery golden brown (although I've heard of green - I've never seen it)
In short - if its more gooey - its cyano - dusty its diatoms.
If its diatoms - look for sources of silicates - usually in the water - top off or water change. Cut the source of silicates and they will run their course.
If its cyano - then its nutrient based - usually an inbalance in phosphate and nitrates. New thanks with low P and low N will get cyano because nothing else can get enough nitrogen to grow readily. (cyano can use dissolved N2 gas directly from the water).
Sometimes the configuration of sand beds are the source of chronic cyano problems as they can leech nutrients depending on composition, flow, pH and age.
If you suspect the sand bed, keep your pH up add flow over the sand-bed and finally if still no relief - chemi-clean may be your answer.
I don't think your feeding are too much
