I am another Cyano fighter. Instant Ocean standard (non RC). Been having issues on and off, mostly on, since November.
125gallon reef tank, 20 gal sump
lots of LR
I feed mysis/coral frenzy/cyclopeeze every other day, 10 fish (3 clowns, 4 PJ cardinals, 1 chromis, 2 wrasses)
I top off daily with 2 gallons in the winter, 1 in the summer
20-25gallons every 2 weeks, I usually try to change 10-15 weekly. I have a funky work schedule so sometimes its 10 days between my 'weekly changes', sometimes only 4-5.
8 bulb T5 fixture, brand new bulbs 2 weeks ago.
Parameters: 1.026, 79*, NH3-0, NO4-0, NO3- usually 5, don't bother checking phosphates,
TDS of 0 from the RODI, changed filters in that back in December due to a slow production rate, my first filter was pretty clogged but the unit was still functioning
I run Carbon in a reactor and dry skim, I finally broke down on Friday and dosed chemiclean. I lighted out saturday and Sunday, 30 gallon water change sunday night, Cyano is still there but definitely shrinking.
One of my Koralia 1050's spins backwards (need to call for more parts) so I am down to 3-1050's and a Mag9 return for flow. I have a WP-40 on order from the group buy so I am hoping it is mainly flow now. Cyano is definitely worse in low flow areas (to be expected)
I have had Cyano in the past in multiple tanks for varying reasons but this bout has certainly been the hardest. Couple this with a Bryopsis problem from a small free frag and I have had a frustrating winter with this tank.