Yeah, sorry, I didn't mean "kill", but at least reduce it. It didn't work out. I have an oversized sump, and filters are always clean. I am working now on turbulence, since looks like BBA may develops mostly in areas where turbolence is highest, which could produce Co2 fluctuations, and in my tank it is actually present just on the front-bottom of the tank where the water gets pushed strongly from the surface, and turbulence is high. I have changed my main pump trying to reduce current and see if that makes any difference. I will keep you posted.
Thanks!