There is an unending variety of lighting systems available to the aquarist to meet the needs of every application. Make sure you know the lighting intensity and spectrum requirements of the plants and/or animals you are keeping in your aquarium. A general "rule of thumb" is to provide between 2 to 5 watts of lighting for every gallon of water. Live freshwater plants have much more specific lighting requirements than do freshwater fish. In the saltwater reef aquarium, different corals have different lighting requirements as well.
Thorough research on your part will ensure that you provide the proper lighting to meet the needs of all your aquarium inhabitants. Once your have determined what your aquatic inhabitants require, you can identify your ideal lighting system. Please refer to our Lighting Systems Selection Guide for help.
For more information on this subject, please read How to Properly Illuminate Your Aquarium.