Light
The right aquarium lighting
Our model for a perfect aquarium lighting is and remains the sun, because animals and plants have adapted to the sunlight in the course of evolution. Some exceptions are cave dwellers or nocturnal aquarium dwellers which are not dependent on lighting.
The accurate spectrum or the colour temperature don’t really matter to the fish either. It’s more our personal taste which leads us to favour a lighting type. For the plants this is an entirely different story: they use the spectral components of the sunlight to generate energy through photosynthesis. If the visible light we supply differs too much from this light composition they are used to, photosynthesis will come to a halt and the plant won’t be able to grow optimally. Therefore we should always aim for a sun-like spectrum.
There are fish species which don’t like to be in bright light. As you probably keep such fish species with others and have plants in your aquarium, adapting the light won’t help much. Instead it is important that these fish species are given places to retreat and hide in. Floating plants, roots, stones and plants provide a means of creating “dark” areas, even in a bright aquarium.
The right light for aquarium plants
Using a floodlight to light your aquarium would not only lead to huge electricity bills, your plants would grow badly too. Strong light intensity alone is not enough!
All plants (land and water) have evolved to adapt to the full spectrum of sunlight and they use the energy for photosynthesis, i.e. for their food production. For photosynthesis, the plant requires the whole spectral range of sunlight (visible in the rainbow or prism) for its source of energy, plus water and CO2 (carbon dioxide). From this it produces sugar (its food), and oxygen is released as a "waste product".
Compared to fluorescent tubes LED lighting means you can save energy, increase the light quantity and individually adapt the light colour. For planted aquariums it is important that the LED lighting has two characteristics: the light definitely ought to have a full spectrum and a high PAR value.
The difference between fluorescent tubes for living rooms or bathrooms and special tubes for aquatics are the number of pieces and the spectrum. For our living areas it’s only the visual impression which counts, whereas for plant aquariums ALL spectral ranges of the visible light are essential. JBL therefore has developed full spectrum tubes. Inside the full spectrum tubes are differences which can easily be seen with the naked eye: the colour temperature, measured in Kelvin (K) provides information how warm or cold a light appears.
A daylight tube, such as the JBL SOLAR NATUR T8 with 9000 K appears rather cold, whereas the sunlight tube JBL SOLAR TROPIC with 4000 K appears significantly warmer. The Danish professor Ole Pedersen found out during a tube comparison that the JBL SOLAR TROPIC exerts the most positive influence on the plant growth!
Red-blue tubes, such as the JBL SOLAR COLOR are very popular as they accentuate the colours of the fish even more. But they are NOT beneficial for a healthy and thriving plant growth.
Quite a lot of aquarium lights have two tubes. We advise you place a „plant tube“, such as the JBL SOLAR TROPIC above the plants, which means the background, and the second tube, which is either a bright daylight tube, such as the JBL LED SOLAR NATUR or the colour-enhancing tube JBL SOLAR COLOR to the front above the fish.
Measurements during JBL expeditions in the tropics yielded lux values between 100,000 (Amazon, Africa; for more information see Expedice ) and 160,000 in Australia ( Expedice 2015 ). Aquarium lightings are far away from reaching these natural values! A 30 W tube in a 20 cm distance generates merely 1,200 lux. A good high polish reflector, such as the SOLAR Reflect T5 /T8 increases the light intensity up to 3,370 lux. As you can see the investment in an aquarium hood with several tubes, compared to only one tube, can be very useful!
Regardless of whether you illuminate with fluorescent tubes or with LEDs, you’ll often read the following rough guidelines for the ideal amount of light: Less than 20 lumen/litre is too low for all plant species. Up to 40 lumen/litre is sufficient for plants with low to medium light requirements. 40 to 60 lumen/litre is ideal for species that require a lot of light, such as lawn plants. Aquascapers always need more light. Lumen specifications can usually be found in the product descriptions of the lamps. In the case of the JBL LED NATUR 44 Watt, 4800 lumens are stated. If you divide the 4800 lumens by your number of litres, e.g. 200 litres, you get 24 lumens per litre. If you were to follow these internet tips one 44 watt LED would only be sufficient for low-light plants and you would need two JBL LED SOLAR NATUR light bars for aquarium plants which require more light. But this is NOT the case!!!
This is where the PAR value comes into its own. If the quality of light is not optimally matched to the needs of the plants (low PAR value), even the greatest quantity of light (lumens) is of no use! A well-known example of this: In office lighting, only the lumen value is prescribed and sometimes it is so high that employees find it dazzling. Office plants that don’t stand near the window usually wither away and die because the light is bright but it does not provide any of the radiation the plants need for photosynthesis. This growth-relevant radiation is indicated by the PAR value. Measurements and tests have shown that PAR values above 200, such as the JBL LED SOLAR NATUR, lead to a reduction in the amount of light required and only half (50 %!!!) of the amount of light is necessary to promote the growth of plants that need intense light. In addition to all the measurements, we aquarists can simply see for ourselves: Switch to ONE JBL LED SOLAR NATUR and start with a slightly dimmed output. Increase the amount of light as you dim it and simply observe your plants to see if they react positively. You will notice that your aquarium plants are already growing visibly stronger with a reduced light output than with your previous lighting. Very often you will not even need the maximum power level! The maximum output of the JBL LED SOLAR NATUR may only be necessary with a few plant species, especially with lawn-forming ones.
The right lighting for aquariums. What does the PAR value mean and how important is it for aquarium plants?
Biologist Heiko Blessin explains the significance of the PAR value (photosynthetically active radiation) for aquaristics in a tropical water in southern Japan.