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What to know about aquarium lighting
June 02, 2021
Aquarium lighting is very important, because by the light, we can see all the beauty of the world encased in glass. If that were the only reason we need light, it would be very easy. But like everything in aquaristics, nothing is as simple as it seems. Aquarium lightings need to be adapted to different kinds of aquariums. For example, a completely different lamp colour is needed for a marine aquarium than for a freshwater aquarium.
Colour temperature (K)
For freshwater aquariums, the general rule of thumb is to use lamps with a colour temperature of 6,500 Kelvin, while marine aquariums should need lamps with a colour temperature of 10-15,000 Kelvin. These provide a colour composition that is suitable for the plants (corals) growing under and also gives a natural, authentic look to the human eye. (We feel that it looks like a real freshwater or underwater scenery). However, this measure is a bit deceptive, as a given colour temperature can be composed of a mixture of many colours at a certain ratio. One way to describe this is that a particular hue of a paint can be blended from countless colour combinations. However, it is important to know that aquatic plants can only use a certain range of colours. Generally speaking, the blue or red range of light. But recent studies show that plants also need green wavelength light. But the green colour range is much more important for us, because it makes the underwater view look natural. This is why most aquarium light sources (nowadays almost exclusively LEDs) feature a so-called full spectrum. The more expensive lights are made up of WRGB (white, red, green, blue) LEDs, while the simpler ones have 6500K broad-spectrum LEDs. WRGB LEDs can usually be adjusted to any colour that you prefer.
So, if you want a modern light over your aquarium, choose from LED lights, but if you're looking for a budget-friendly solution, check out our range of fluorescent lights. However, slowly and surely, LEDs are replacing their outdated fluorescent equivalents.
Luminance (Watt, lumen, PAR...)
Almost the most important selection factor is to ensure the right level of luminosity. There are several factors to consider when making a decision.
How big is the aquarium?
The surface that needs to be illuminated is important, so choose a lamp that has the same length as the aquarium or has a diffusion that provides enough light at the edges.
The depth of water which you have to reach with a certain intensity of light is also essential. Of course, this is only really relevant if you want to grow plants close to the substrate level. The best metric to answer this question would be PAR, but this is the hardest to find on manufacturers' datasheets. PAR represents the intensity of the wavelength (400-700 nm) that covers the spectrum of light needed for plant growth. If this number is not found, the next measure of light intensity is the lumen. This is also adequate, except that it includes light spectrums that are not visible, which slightly compromises the accuracy. Manufacturers almost only indicate this number and the power (wattage). No matter, these numbers are at least comparable.
What's the right one for me?
If you mainly keep fish and a few easy plants (anubias, mosses, bucephalandra, etc.), you can choose a lamp with around 10-20 lumens per litre. This will give you a slowly developing aquarium with only a few algae problems.
If you're already thinking about meeting the needs of your plants, choose a more powerful lamp. 20-40 lumens per litre should be adequate. You should also consider the CO2 injection because, with this light, nutrients, and carbon dioxide, the aquarium will sparkle. At this luminance level, you should also pay attention to the cleaning and proper filtration of the aquarium because at this level, the high luminance can cause algae growth.
Finally, the high-intense lights are the ones at a range of 40-70 lumens per litre or above, which can bring out the deepest red from your plants. But here, any mistake can lead to algae growth. Use this luminous intensity carefully. No question that without CO2 dosing, you won't even try.
How many hours should the lights be turned on?
The ideal daily lighting period for an aquarium is 8-10 hours. It is worthwhile to use a timer to leave the light on when you are away from home. More advanced LED lights already have their timer, but a mechanical timer will also do the job without one.
How long will LED lights last?
With a bit of exaggeration, modern LED lamps have "eternal life and a bit". The exact definition is that the lifetime of a LED ends when its luminous flux drops to 70%. This is usually estimated at around 50,000 operating hours. The specific expected lifetime depends on the operating current and operating temperature of the LED. It is interesting to note that transformer failures occur more often than LED light source failures.
Should I choose a suspended or a top-mounted lamp?
Both options are good. If the lamp is suspended, it is easier to trim plants or carry out other maintenance underneath. To set up the suspension accurately, you need to pay attention to the point at which the lamp is not just lighting the aquarium but also spreading light on the floor next to it. This is the point above which the lamp is not worth raising. The disadvantage of the suspension is that the lamp may shine into your eyes. In this case, it is recommended to use a deflector/shader attached to the armatures. Many people don't leave it to chance and cover the top-mounted lamp because of the light reflection from the water.
To sum up, when choosing a suitable lamp, you need to know how much luminosity you would like to provide to your plants, how much surface area, and how deep you want to illuminate. Also, whether you want it suspended or mounted on the aquarium. While these thoughts are swirling in your head, we wish you a pleasant browsing through the endless selection of Green Aqua lamps ... :)