Why does pulling from the top matter? Hmm, if you pull from the top and have the powerheads blow on the bottom you might get more turbulance, which I'm guessing is good. But that got me thinking, if I used 2 powerheads and pointed on at the glass, that might really keep the water mixing1
Yeah, the only reason I'm pulling from the top is because of the way I designed the flow of the tank. I've got what is supposed to look like a 6" wide stream bed running down the center of it with plants on each side and I wanted the water flow to be concentrated in the stream bed. The spray bars are hidden in small caves that I created so the main part of the flow stays in the stream bed. Not any better or worse of a system. It was just a fun idea to try. I originally made it that way hoping to see rainbow darters in the current in the stream bed, but it seems that the bigeye chubs have taken up residence in the current. Interestingly, the chubs were collected in a calmer portion of the stream and the rainbow darter was collected right in the current.