I am also an aquarium hobbyist. While between theatre gigs, I have worked @ a hardware store, which gave me time to wander the aisles and "figger". I built a coral reef system in 3 tanks, a main display, a filter sump, and a "refusurgium" upstairs one level. The refusurgium is a divided tank with relatively slow flowing water on one side, and a device to collect and flush water (about 12 gallons) downstairs into the main display in a tidal surge every 4 minutes. It was noisy and annoyed the GF, so I came up with a way to control a valve electrically to turn the flush one and off. I hooked up all of my lighting, and the valve, to a computer-controlled bank of relay switches. I enclosed the relays and controls in a hood that I built for the upstairs, where I had seahorses. I also bent conduit and welded a light stand to support my metal halide lights downstairs.
Here is a link to a reefer's forum that I documented the project in:
http://www.thereeftank.com/forums/f76/refusurgium-hood-project-59821.html?highlight=refusurgiumIt was a very cool process.