[stevedola]

Brian,
To increase water volume but continue to stay within your limitations you could employ a small 10 gallon gravity fed fuge that almost sits upon (with some stand mods) the 29g sump. The drain from the 75g could be split and valve to have water enter the fuge and sump and have the fuge simply drain into the sump for return to the main tank. This would give you almost 40g of added volume and still stay with in your limits. Ive seen it done and worked quite well. If you needed more flow you could just add a small power head to keep water circulating. Just an idea-