Power compact aquarium lights are a type of fluorescent fixture that can be used for both freshwater and saltwater aquarium systems. Power compact aquarium lighting is widely used among hobbyists because it is a low energy solution. They can be used by themselves or in conjunction with metal halide lighting. Power compact light bulbs should be replaced every 9-12 months. Power compact aquarium lights are great for fish-only systems and reef aquariums with corals that require low-to-moderate lighting.