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Lighting an Aquarium

By: Jennie Kermode - Updated: 19 Jun 2014 | comments*Discuss
Lighting Illumination Aquarium Fish Tank

Every aquarist wants a beautiful looking tank so choosing the right lighting system is an important part of setting up. What many people don't realise is that it's also important to the health of your fish. Fish with the right lighting system will be more energetic, more brightly coloured, more resistant to disease and more likely to breed. A well lit aquarium also means healthy plants, which make for a healthier ecosystem.

Day and Night

Just like people, the majority of fish have a physiological cycle which follows the cycle of night and day. Too much day and they won't get the rest they need; too much night and they'll become listless, losing their colour and developing problems with the routines which keep them healthy. If you get up late or stay up late in the evenings, artificially lighting your home, your routine may not suit your fish. You can get around this by establishing a regular cycle with aquarium lights, which can be turned on and off manually or by means of a timer. If your fish are used to an aquarium light, they won't be kept awake by other lights in your home after it goes off, because of the difference in brightness.

Most fish breed only at one time of year (usually in spring) and establish their breeding cycles according to the changing length of day and night. To encourage your fish to breed you should make sure that your aquarium light is on for a slightly longer time in summer and a shorter time in winter.

Lighting and Plants

A healthy aquarium relies on healthy plants. Plants help to oxygenate the water, provide a secondary food source for your fish, and provide the shelter and privacy which many fish need in order to thrive. However, aquarium plants will not usually get enough light to survive without artificial help. A standard aquarium light will improve your ability to keep healthy plants, but a heavily planted aquarium can benefit from extra lighting and your plants will do better if they have access to light with a spectrum similar to that of sunlight. Like fish, they will benefit from a standardised day and night cycle.

As well as encouraging the growth of plants, lighting encourages the growth of algae, which can obscure your view of the tank and can, if it gets out of control, be harmful to your fish. For this reason it is important to keep an artificially illuminated tank well stocked with plants at all times. When you don't have enough plants, algae will use the light which is left over.

Types of Light

In choosing a light for your aquarium, the most important thing to consider is how much heat it gives off. A hot bulb can present a fire risk and can make the temperature of your aquarium hard to control. For this reason you should avoid using incandescent bulbs or halogen bulbs. Your best option for a standard tank is to use fluorescent strip lighting, preferably T8 quality. If you have a heavily planted aquarium you may prefer to use metal halide bulbs, which generate much more intense light, but you should be aware that these can cost literally ten times as much and they are not necessary in most cases.

It is always wise to use a hood on your aquarium, as this prevents fish from jumping out and also reduces evaporation. Many hoods come with lights already fitted, so all you need to do is change the tubes. You shouldn't necessarily wait until they die to do this. Most fluorescent bulbs lose much of their capacity after just six months, reducing the spectrum of light they produce, so if your bulb is older than this you should consider changing it if your plants appear to be struggling.

Most tank hoods only have room for one or two fluorescent strips, which may not be sufficient for all your plants. Some hoods, however, do not contain light fittings but instead have a glass panel above which you can position other lights according to your preference. These are often the best option for a heavily planted aquarium.

Once you've chosen the right lighting system, you'll be able to sit back and watch your aquarium blossom as your plants and fish respond to it. Lights which are good for plants also help to bring out fish colours so that you can enjoy them at their very best.

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URGENT : - Please could you advise me?I have a small tank (50litres) containing one paradise fish and a "family of platys and lots of growing plants, and need to replace the strip light which is a marine white 18", 14k. One shop near me only has coloured strips suggesting that the orange one could do.These are cheaper than another shop I have contacted who have the white strip light but it is more expensive. Would it be OK to buy the orange strip, what benefit would an orange light offer the plants or fish or is it better to stick with white? Thanks for your answer, in anticipation, Helena.
hellybelly - 19-Jun-14 @ 10:24 AM
I have just started rekeeping tropical fish and have brought a tank with light's in the top,previously when I had fish there was always a glass or plastic section over the tank under the lid to protect the lights,this new set-up does not have any plastic or glass and the lights get wet is this safe?
cazham - 29-Oct-13 @ 4:42 PM
I have just purchased a already stocked tank ( owner going overseas ), theres one angel fish in the tank, i would like to add another, does it matter if they are the same sex ?,how do you tell if i've got a male or female. Thanks
fastbiker - 13-Sep-12 @ 3:58 PM
Thanks for the article, very good for beginners.
Deny - 5-Apr-11 @ 10:43 AM
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