For many aquarium keepers, energy efficiency is key. To see just how much electricity your aquarium is using, try hooking up a Kill-A-Watt meter to your equipment. This device will allow you to pinpoint your energy hogs so that you can make an informed decision on how to reduce your costs. The largest consumers of energy on any reef tank are the lights and the return pumps usually. Modern powerheads only use a fraction of the electricity they used to, and protein skimmer pumps are also becoming quite energy effective.