Cyano trouble

[Biulu]

Normally every autumn there is a period of about a month that cyanobacteria show up in my tanks. It has been blamed on a drop in temperature coupled with different chemicals being put in the water. However this year, I have had it all winter and still now that temps are going up again, I am still suffering from it. I have tried everything from 80% water changes to adding more nitrates and flow and the only thing I notice is that disturbance seems to make it worse.

Sometimes I read it is a lack of nitrates and other times I read, it is too many nitrates. Any suggestions of what to do?
The main tank is a 80 gallon rimless, with a dirt substrate capped with sand, medium light (T8s that were recently renewed), no CO2. I am willing to tear it all apart and choose a different substrate if need be.

TIA!