Like melosu asked (Feeding frequency - and what are you feeding?), and I'm also interested in what kind circulation you got in the tank. PHs, how many and what gph
If feeding frozen brine or myisis, I've heard that the water that stuff comes in (frozen of course) contain LOTS of phosphates. I now rinse mine with fresh water after it thaws.
How long ago did the MH
lights go in?
Also, check your phosphate readings from your ro
. Just curious if the filters are OK and need changing.
IME, cycano is reddish and diatoms are brown.