well, I backed off the light cycle yesterday (down to 6 hours now), bumped the CO2 to about 3 bubbles/second (no drop checker at the moment) and stopped with my EI ferts. Also picked up 20 ghost shrimp as I couldn't find Amanos at the time. We'll see if they do any good. Anyways, I'll keep removing it manually with a tube/bucket every night for a while and see if I can get it under control.
It started right after i tackled a case of greenwater with a UV - I suppose the high nutrients were still in the water column and had to go somewhere.