Well, back to lighting then. You have many options, some of which are more efficient than others. High output T5 fixtures are used frequently, as well as metal halide units, but the newest technology is LED
lighting. if you choose metal halide or T5, your bulb replacement costs(between 8 and 12 months) and also electric usage should be considered. LED
is the most potent and most efficient lighting on the market to date, but it's quite new. LED
boasts 50,000 hour life spans and very little heat and electricity consumption, making them the best choice in my experience.
Generally the more potent units come in smaller fixtures. You would need 2 of them over a 4' tank.
Depending on what options you want, you can spend anywhere from $150.00 a fixture, up to about $800.00 or more. Both ends of the price scale will grow corals, but the more expensive fixtures come with extra options like a fade in and out to simulate morning/evening transition, cloud cover, even lightening storms. Please note that all of these options are for human enjoyment and do nothing for photosynthetic creatures.