Lighting your aquarium
In addition to TH and THC, pH, CO2, heating or filtration (ie clean water and NH3 content), one of the most important parameters for health and quality of life Of your fish is lighting. Light is one of the parameters determining the health of your fish, especially the respect of the biological rhythms, as well as for the growth of your plants (photosynthesis). To master this aspect of the aquarium, it will be important to know what equipment to use, how to position it, and to respect a reasonable lighting duration, luminous spectrum and luminous intensity.
The qualities of the radiation used
The characteristics to be respected for good lighting are essentially the luminous spectrum, also called temperature (expressed in degrees kelvin, or ° K) and the intensity of the illumination (expressed in watt, or W)
For indication, the reference used is the temperature of the solar radiation, which is located at around 6500 ° K. The lower the temperature of the lamp, the more the light spectrum will turn red. Conversely, the higher the temperature of your lamp, the more the light spectrum will draw towards the blue.
In aquariophilia, it will be important to respect a temperature around 6000 ° K. It will thus be quite close to that of the sun, without too much promoting the growth of algae.
It will be determined according to the requirement of your plants.
Some plants require a low intensity: it will be necessary to apply a power of 1 watt for 4 liters of water.
Other plants require medium lighting: a lighting power of 1 watt per 3 liters of water is recommended.
Others require intense lighting: a power of 1 watt per 2 liters of water is then indicated.
Finally, for plants requiring very intense lighting, a power of 1 watt per liter of water will be applied.
The duration of the lighting
It will be necessary to ensure maximum lighting periods of 15 hours. The ideal is to light your aquarium only 12 hours. The overall amount of light does not matter: you should not try to compensate for a light that is too low for a longer duration, or, conversely, for a light that is too strong for a shorter duration.
Absolutely avoid discontinuous lighting, which disrupts biological cycles of your fish as well as your plants.
The positioning of the lighting.
In nature, the illumination is vertical. This is what you need to do for your aquarium: the lighting system should be positioned on top of your tank. A reflector may advantageously potentiate the intensity of the light emitted. Also avoid placing a glass plate between the lamp and the surface of the water, otherwise it will lose up to 10% of the light output (or more if the plate is dirty ...). Also avoid placing your aquarium in front of a window, a light source lateral that will promote the growth of algae.
Types of lamps.
There are essentially two types of lamps: fluorescent tubes and halogen lamps.
These are the most commonly used. It is important to use only tubes dedicated to the aquarium: domestic lighting tubes do not diffuse the same spectrum of light, and are not adapted to this type of use.
They should be changed twice a year, as their performance decreases gradually, invisibly to the naked eye. Failing this, the growth of plants is slowed down and that of the algae is favored. In order to ensure a certain continuity in the overall result obtained, and to avoid variations in intensity that are too sudden, it is also advisable not to change them all simultaneously. An interval of one month between each tube is advised.
They are recommended when the depth of the aquarium exceeds 80 cm. Higher lighting power is required, and halogen lamps meet this requirement. On the other hand, they should be placed between 40 and 70 cm from the surface of the water, in order to prevent them from influencing the temperature of the water. It will also be necessary to think to arrange a UV filter. The lifetime of these lamps is about one year.