But I think I need to stick with what I have for a while, and get things tweaked precisely to nix the thread algae and BBA that keeps cropping up here and there. It seems to be mostly on older buce leaves, now, which I am slowly removing one by one.
Filter was still not quite right- yesterday I noticed a trickle coming down the spillway, and this morning it was a steady little stream. So during maintenance I turned it off and pulled the media out again- no clogs. Lifted out all the bio-cubes and had a thought. There's ridges in the bottom of the HOB box, both sides of the panel, maybe they have a purpose. Smaller bio-cubes settle down between them. I took them all out and replaced with larger, ring-shaped ceramics. (Half were already those type anyway). Put it all back together and voilá! No more overspill. Not even the smallest amount. I forgot to replace the loop of fishing line that held the sponge and poly batting onto the panel, but it doesn't seem to matter- the flow holds them in place. Very pleased. Fishes are playing again.