How to choose right LED lights for planted aquariums?

All plants need light for growth, but aquariums can’t simply be placed by a window to solve this problem. Excess light is a major cause of algae growth in aquariums. The best way to manage the lighting of an aquarium is to place your aquarium in a position that receive absolutely no sunlight and rely entirely on artificial lighting.

It is true that sunlight contributes to the health and luster of fish, but ultraviolet light is unnecessary for bringing out the beauty of aquatic plants. In fact, aquatic plants raised indoors will turn out much more beautifully than those cultivated outdoors.


There are several options for lighting, including mercury bulbs and halogen lamps, but LED lights are the best economically, aesthetically, and practical.

The intensity of light necessary is related to the amount of CO2 being added. If the light is very intense, but the plants don’t receive a correspondingly amount of CO2 comparatively, then the light will cause more harm than good.

If, on the other hand, the amount of CO2 is increased without a corresponding increase in lighting, the plants will not photosynthesize well, and the CO2 level will reach such a level that it will become toxic to the fish and invertebrates.

The balance between light and CO2 depends on several factors, including water temperature and plant types. Plants can be divided into two major types here: high light plants (require strong lighting conditions) and shade-loving plants (grow in shade).

High -light plants require both intense amount of light and CO2 rather than shade-loving plants. Such plants as Anubias and ferns are considered fairly easy to cultivate because they are shade-loving plants. They are highly adaptable to strong light environments and so are the most flexible plants.

Such plants as the Dutch plant and the needle leaf, which have narrow leaves and red stem coloration, are said to be difficult to cultivate, but this is because they require relatively high levels of both light and CO2. They aren’t flexible like shade-loving plants, but they are not different from other plants in any other respect.

Following is the thumb rule for choosing LED lights for planted aquariums, which is based on PAR (Photosynthetically active radiation):

  • PAR 15-30 for low light plantsĀ  such as moss ball, anubias, ferns…
  • PAR 35-65 for moderate light plants including most stem plants
  • PAR 65-90+ for high light plants such as needle-leaf, red plants. And you will need to supplement CO2 to avoid algae problems.

When setting up the aquarium, it is important to try to place the light-loving plants directly under the bulbs, and reserve the spots that receive less direct light for the shade-loving plants.

Let’s look at some concrete examples. In a 24-inch tank, we cultivate Cryptocoryne and Anubias, both are broad-leaved, low photosynthesizing shade-loving plants, they should be positioned in places with PAR output of around 30.

In the same tank, however, light-loving plants, such as the aforementioned red stem plants, should be positioned directly under the light so that they meet their PAR requirement of around 90 and CO2 injected is required in order to keep the plants healthy.

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