Duration of lighting in the aquarium
Moon phases – with the right lighting in the aquarium too
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Important basic data for lighting in the aquarium:
The lighting duration of an aquarium is usually between 10 and 14 hours.
Many plants fold up or fold their leaves when they have received enough light.
However, not only the plants have demands on the lighting duration. The aquarist also wants to have light in the aquarium after work.
Many aquarists shift the “day” in the aquarium into the evening compared to the current time of day, e.g. B. 10:00 a.m. – 10:00 p.m.
If an aquarium has several lamps, it is advisable to control them separately with different timers. With this you can simulate something similar to a sunrise and sunset with simple means. A corresponding electronic control is of course even better. The animals are not so frightened and sometimes develop completely different behaviors in the transition phase.
Depending on the requirements, a light break at midday can be useful. Then you can illuminate longer in the mornings and evenings without increasing the total duration of the illumination. The lunch break is usually two to four hours. Whether the lunch break helps against algae is controversial.
It is just as controversial whether such a break corresponds to the conditions in the tropics. On the one hand it can get very dark in the tropics when it rains, on the other hand the aquarium lighting is very weak compared to the conditions in nature.
The service life of the fluorescent tubes only changes by between 10 and 20% due to the more frequent switching on and off during a lunch break.
In practice, there are aquariums with good plant growth and without algae both with and without a lunch break.
There are separate articles in the for the following lamps
Energy-saving lamps for aquarium lighting
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Energy-saving lamps are suitable as aquarium lighting. The strength of the lamps should be 1/4 to 1/3 watt per liter of water.
Energy-saving lamps are fluorescent lamps with three-band phosphors. They have a high light output and a long service life.
Because they are intended as a replacement for incandescent lamps, there are practically only energy-saving lamps with light color 827, ie warm tone internals. The plants get along well with the light color, but many aquarists find the color very yellow. An exception with a different light color is Osram Floralux.
The lamp socket should be splash-proof.
A ballast is integrated into the housing of energy-saving lamps. Lamps that go on immediately after switching on and do not flicker first have an electronic ballast (EVG). Cheaper versions have a conventional KVG ballast with choke and glow starter. The ballast must also be disposed of, while only the starter should be replaced with fluorescent lamps.
Other disadvantages of energy-saving lamps compared to fluorescent lamps are the shorter service life and the lower light output.
The average service life, ie the time up to which 50% of the lamps work, is approx. 10,000 hours for energy-saving lamps. For normal fluorescent lamps, the service life, ie the time until 80% of the lamps work, is about 10000 to 14500 hours.
With energy-saving lamps, the light output is between 33 and 65 lumens per watt, at 3 watts or 23 watts. A normal fluorescent lamp with 30 watts achieves lumens per watt with CCG 59 and 72 with ECG.
Compact fluorescent lamps have an external ballast and are also available in all available 800 and 900 light colors. These lamps have a plug connection between lamp and ballast. So only the lamp and not the ballast needs to be changed. However, the plug connections are not splash-proof or waterproof.
The meaning of light color
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The growth of many plants is influenced by the color of the light, the light spectrum and the light intensity. Some Cryptocorynae z. B. are green or brown depending on the light color and light intensity. The light color does not seem to have any effect on other plants.
The role played by light color and the influence light intensity has on the growth of plants is always a subject of heated debate.
According to one interpretation, the light color plays the decisive role. According to the other view, only the light intensity plays a role.
Professional plant breeders illuminate their plants with extremely yellow-red light without blue components. However, low-pressure sodium vapor lamps have the highest efficiency of all light sources. With up to 190 lumens/watt, these lamps achieve four times the light output of mercury vapor lamps and two to three times that of fluorescent or HQI lamps. The service life is also longer. Because energy costs are one of the biggest economic factors for plant growers, these lamps are ideal. The fact that algae may not thrive so well in this light is a pleasant side effect. Better plant growth based on the light color cannot be concluded from this.
Plants may need certain amounts of certain colors of light. If these amounts are definitely reached under strong light, the influence of the light color of the lamp under strong light may become less. This would at least explain why, according to the experiences of many aquarists, plant growth does not seem to depend on the light color of the lighting when there is strong light.
Lamps with a light spectrum that is as similar as possible to daylight are recommended for aquariums. These are fluorescent lamps and HQI lamps.
The color rendering index, which measures the color fastness of a light source, is almost identical for both types of lamps. The Ra is determined by comparing 14 test colors under the light source to be assessed and under a reference radiator of the same light color.
With both lamp types, there are lamps whose color rendering is rated 1a, ie very good. These lamps can be recognized by the 900 light colours. With fluorescent lamps z. B. 930 and 950 with fluorescent, with HQI lamps from Philips, the CDM, the light color 942.
The color of the plant that the aquarist perceives is that part of the spectrum of light that is not absorbed by the plant, but is simply reflected. It therefore makes no sense to illuminate a red plant with a light that has predominantly red components in order to improve the growth of the plant. At most, the subjective color effect is increased. This plant can only generate very little energy. As a result, the rate of photosynthesis decreases drastically. In addition to the light intensity and light color, the color of the plant also plays an important role, although many species can also change their color.
How strong the lighting should be
In aquariums with a water depth of up to 40 centimeters, a light quantity of 0.4 – 0.5 watts per liter of water has proven to be effective for plants with medium light requirements using fluorescent tubes. The amount of water actually available is used as a basis, not the external dimensions of the aquarium. In deeper aquariums, either plants with lower demands on the amount of light or other light sources should be used.
The specification in watts per liter is only a guide. The shape of the aquarium, the depth of the water, the light requirements of the plants, the density of the planting, etc. influence the amount of light required.
If you take the amount of light in nature as a guide, an aquarium would have to be illuminated with 4000 watts per square meter. In comparison, practically every aquarium suffers from a lack of light. On the other hand, there are also shady areas in nature, etc.
The following graphic shows the course of the illuminance at different water depths with an 18 watt fluorescent tube in a 120 liter aquarium with a height of 50 centimetres:
Illuminance in a 50 centimeter high aquarium Photo: Ernst Artur Helder
How to control aquarium light automatically?
With the help of a light control, the dawn and dusk should usually be simulated.
In principle, light bars can be dimmed if dimmable electronic ballasts (EVG) are used. Existing conventional ballasts may have to be replaced. Dimmable electronic ballasts can be recognized by the two additional terminals for the 1 – 10 V input. At Osram, dimmable electronic ballasts have the suffix DIM in their designation, at Philips they are called “Regulator”. Electronic ballasts with a 1 – 10 volt interface can be used e.g. B. with the IKS Aquastar.
Appropriate light controls are commercially available, but expensive:
- Lightbar and control from Luxor – expensive, few control options
- Giesemann lights with built-in twilight control – expensive
As an alternative, you can build your own lighting controls. Dimmable electronic ballasts are used, e.g. from Osram. These are controlled with:
- ready control from Luxor
- with IKS Aquastar. The SimmMod 1 – 10V module – starter is exchanged for the Aquamemolux starter. But then it is not dimmed enough. There are also reports that the starters often fail.
- AMTEL processors
- single board computer e.g. B. Conrad electronics
But even these self-constructions are sometimes expensive. Inexpensive solutions require more handicraft work.
Simple and inexpensive solutions are available when several light sources are available. In this way, 2 or more fluorescent tubes can be switched on and off with a timer in such a way that the individual tubes are switched on one after the other at a distance of e.g. B. 10 minutes. To do this, it must of course be possible to switch the tubes individually.
An inexpensive and simple solution can practically always be implemented by switching on a very small energy-saving lamp. This is switched on with a timer before the main lighting is switched off. Later, after the twilight phase, it is switched off. In the morning, the energy-saving lamp is switched on in front of the main lighting and switched off when the main lighting is on.
Why night lighting can be useful
Night lighting can be useful if:
- brood-caring fish do not normally watch over their young at night
- nocturnal fish should be observed
- Fish are startled when the light is suddenly turned off
Suggestions for night lights
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Children’s night lights can be put to good use. There is e.g. B. Night lights with photosensitive resistors that turn on automatically when the lights go out and turn off when the lights come on. Lights that are too bright can be darkened with foil etc.