The only waste when going bigger usually has to do with adding depth to the tank. Ideally, the longer and wider the tank, the better -- a 6ft long shallow tank is better than a 4ft long tall tank. Most fish appreciate staying lower in the water column. Plus, the deeper the tank, the more powerful your lights need to be.
Acrylic, 250 lbs Fiji/Tonga mix, 3x175 watt MH
& 2X96 watt PC
, 1/5hp Arctica chiller, EV-180 skimmer
Brown Tang, mated pair Clowns, 4 Fire Gobies, 13 Chromis, Orangespotted Sleeper Goby
Some corals and inverts yet to be identified!