The lighting in your aquarium is very important for two reasons. Most importantly it is needed to the health and well-being of the fish and plants living in it. But it is also important from an aesthetic point of view. An aquarium can be a large and imposing piece of equipment, and without appropriate lighting, it can look dull and uninteresting.

So there are two main questions to be answered in relation to aquarium lighting. One is how much lighting do you need and the other is what type of lamps should you go for.

As mentioned above, the quantity of lighting depends on what you are keeping in the aquarium and it's depth.

If you are only keeping cold water fish and only a few, or no plants then you will only need a single lamp.

Tropical aquariums, which always look best when they have a lush planting of aquarium plants, will require more lighting. In this case you could either use more lamps, or ones that have more output.

Marine aquariums containing coral, or invertebrates, require the highest amount of light and would therefore need either three or more standard lamps, or the use of high output lamps.

The depth of the aquarium will also affect the required light levels, obviously, the deeper the aquarium the more lighting you will need to penetrate all the way to the bottom.

The most common type of lamps used in aquariums are fluorescent tubes. They come in varying lengths and wattages, but the main two types used in aquarium lighting are T8s (1" in diameter) and T5s (5/8" in diameter). The smaller T5s are available in a high output version which output approximately one and a half that of a standard T8. This means that for cold water aquariums, small aquariums, or aquariums with few plants the standard T8 fluorescent tube would be fine. Where as if you have a tropical aquarium, you may be best going for a couple of T5s.The intensity of the light from fluorescent tube can be improved by using reflectors, to focus more of the light into the aquarium.

The other main type of lamp used in aquarium lighting is metal halide. These types of lamp have a much higher output than the fluorescent tubes and are therefore more suitable for use in the marine aquariums, where the inhabitants are used to living in areas with intense light, or in very large aquariums. These are generally much more expensive than the fluorescent tubes, but give out a more 'natural' light.

You may even decide that to get the visual affect you desire, that you want to use a combination of both fluorescent tubes and metal halide lamps.

It is also worth remembering that most aquatic lifeforms are accustomed to a photo-period of 12 hours light and 12 hours dark. To this end you could employ a timer switch at the socket to automate this process, or in some of the more expensive metal halide systems you can get computer assisted functions that replicate the current lunar cycle, which believed to influence the spawning of corals.