Nothing adds character to a freshwater home aquarium quite like the gentle green foliage and bright colors of aquatic plants.
While many people still opt to use plastic plants in their aquariums because they do not require any care, there is a growing appetite for raising fish in planted aquariums.
New aquatic plant trends, such as growing marimo moss balls, are becoming more and more popular.
Underwater plants need access to the full light spectrum. Ensuring your aquatic plants receive the right amount of light can, however, be tricky. If your aquarium gets too much light, algae will start to grow.
LED (Light-emitting diode) lights are a great way to be able to control the light conditions in an aquarium.
They allow you to achieve a lighting balance that encourages plant growth without exposing the water to so much light that it becomes a hospitable environment for algae to thrive.
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Can LED lights grow aquarium plants?
To grow aquarium plants, use LED lights that burn at between 6,500 and 10,000 kelvins. Match the strength of your lights to the light needs of your plants. The strength of your LED lights needs to be compatible with the depth of your tank, and your system must spread light throughout the whole tank.
LED lights are generally superior to fluorescent, incandescent and metal halide lighting systems and can reach down to 24 inches deep without giving off much heat.
They are also environmentally friendly and consume relatively little energy. LED lights also famously have a long bulb life and can burn for over 50,000 hours.
Types of LED lights to grow aquarium plants
There are several varieties of LED light systems that can be used to grow aquarium plants.
What kind of LED light fixture you choose will depend on several factors, including how much natural light your aquarium gets, how big it is, what kind of plants you are growing, and what aesthetic you are going for.
The larger your tank is, the more powerful you need your LED light’s PAR (photosynthetic Active Radiation) to be. PAR is the ability of a light source to aid plant growth.
You will also want to consider how well your LED light is going to spread throughout the tank. You need the light to reach all your plants for them to photosynthesize. For this reason, you may need to purchase multiple lights.
Because aquariums are as much home design features as animal habitats and plant homes, you can also choose a lighting option based on its look, so long as it is not incompatible with the needs of your plants and fish.
Some LED aquarium lights are made to be inserted under the water. One common kind of underwater LED light comes in a glass tube and is stuck onto the side of the aquarium with suction cups.
If you prefer an aquarium with a variety of bright colors, you might opt for red, green, or blue bulbs.
You can also purchase an LED light system that comes with a “moonlight” function.
These lights are a cool design feature, because they light aquariums up with a blue light at night. They are also good for fish health, because they give off light that is not perceived by fish.
Timing LED lights for growing aquarium plants
When using an LED light to grow aquatic plants in an aquarium, consistency is key. You want your plants to be getting the same amount of light at the same time of day every day.
For best results, purchase a lighting fixture with a timer, or purchase a plug timer and allow your timer to turn your aquarium lights on and off without your interference.
When deciding how to set your timer, consider that you are trying to recreate a natural environment that mimics the movement of the sun, both for your fish and for your plants.
If your aquarium receives some direct sunlight, you will not need to keep your LED grow light burning for as long as you do if it only gets indirect light.
While a little bit of direct sunlight is not the end of the world, direct sunlight does cause algae to grow. You should therefore try to keep your aquarium somewhere that gets bright, indirect light.
You should use your grow light(s) for between eight and twelve hours per day at an intensity suited to your plant varieties.
Dealing with algae
Light is necessary for your plants to photosynthesize and grow. However, if your tank is getting too much light, algae will grow and spread as well.
Not only will this look terrible and turn the water green, but it will also block the light your plants receive, reducing their ability to photosynthesize.
Algae is particularly problematic for floating freshwater aquarium plants, because it grows thickly around them, and prevents them from absorbing the necessary nutrients.
If you have a build-up of algae in your tank, clean it and reduce your tank’s light exposure.
Why are my aquarium plants growing under LED lights dying?
It might also be that your lighting fixture is not penetrating the water down far enough, or that upper foliage is blocking the light access of lower plants, preventing them from photosynthesizing and causing them to die. If this is the case, try trimming your aquarium plants or investing in another LED light for the bottom of your tank. Your plants might also be dying because you are using too much light! If, for instance, your Java Moss is turning brown, you should check that it is not covered in algae, which grows thick and fast when there is a lot of light.
Frequently asked questions about using LED lights to grow aquarium plants
Will it damage my aquatic plants if I leave the LED grow lights on for more than 24 hours?
The short answer is that it will not if it only happens every so often. The longer answer is that it is not good for plants to get that much light. The sun does not stay in the sky for 24 hours a day, and you should aim to keep your lighting schedule regular and consistent.
What plants are the best plants to grow in an aquarium using LED lights?
The most important thing about choosing plants for an aquarium, is that you choose plant varieties with similar light requirements, as this will make it easy to ensure that your plans are getting what they need. If you are starting out, you might begin by growing low-light aquatic plants such as Java Moss, Anubias and the beautiful and frilly anchored aquarium plant, the Java fern, because these are among the easiest plants to care for.
Daniel has been a plant enthusiast for over 20 years. He owns hundreds of houseplants and prepares for the chili growing seasons yearly with great anticipation. His favorite plants are plant species in the Araceae family, such as Monstera, Philodendron, and Anthurium. He also loves gardening and is growing hot peppers, tomatoes, and many more vegetables.