Have you tested you new water for PO4
? I know you say your filters are new but I would check. Its comes from feeding also.
Cyno, low flow in tank and old bulbs when changing spectrum can also help bring it on if there is ANY PO4
in the tank. Trace is enough PO4
for have cyno, the trace is what the cyno is not consuming so there is more the trace in the water.
Are you sure its cyno..
I got it bad in my fowlr
right now, I had none for years then I got new/used PC
lighting and WHAM Cyno over everything. The bulbs in the light must be older then the person told me is my guess. So I am doing water changes and I'm looking at getting 4 new bubls. My tank also tests 0 for PO4
so even though it says 0 I know theres enough to feed the cyno.