I don't know why these threads always dwell on a center support, you don't need a center support at all. I have a 220 stand with only 4 legs total. The center spans 5' unsupported. I'm also using a granite counter top with nothing (foam etc) between the tank and stand/granite.
The guys over at Tidal Gardens use a stack of cinder blocks on each end with a couple of 2x4's and no center brace.
The guys over at Tidal Gardens use a stack of cinder blocks on each end with a couple of 2x4's and no center brace.