How to Pick The Best Planted Aquarium Light

How to Pick the Best Planted Aquarium Light

It all depends on what light you choose for your planted aquarium. This is a common question we receive. Let’s discuss three lighting options and their implications for beginners to help you get started with your planted tank journey.


#1 Color Spectrum

If you have ever compared the lighting in a coffee shop to a hospital, you will know that white lights can vary in their color temperature. These are measured in Kelvins (K). A warm, soft reading light that gives everything an orange glow might have a rating as high as 2700K. While a cool white light with more of a blue tint might be labeled at 10,000K.

To be honest, color spectrum doesn’t matter that much when it comes to growing aquarium plants because they can thrive under a wide range of Kelvin. It mostly comes down to human preference because we don’t want to look at aquarium lights that are too red or blue. Many hobbyists like to use a neutral white light around 5000 to 6500 K because it’s said to best simulate natural daylight. A light can be chosen with any color spectrum provided it’s not too bright (such as the ones used to grow saltwater corals).

Plants can grow under a wide spectrum of lights, so pick a color temperature that you feel makes your plants and fish look the best.

Light Intensity

How bright should the light you use? First off, it depends on what kind of aquarium plants you want to grow. Low light (or low intensity lights) are good for growing anubias and cryptocoryne, crypts, ferns and other non-demanding plants. Medium lights can be used for stem plants, and all other species, except carpeting plants. High lights can grow virtually anything, but often require carbon dioxide (CO2) injection in order to keep up with the fast plant growth and to minimize algae blooms. High light aquariums can be complicated so we recommend that beginners start with low light plants. They are the hardest and most beginner-friendly.

The next question is “What is considered low light versus high light?” The intensity of plant growing lights is often measured as PAR (or Photosynthetically Active Radiation). Manufacturers don’t publish PAR numbers as they are affected by the location of plants, distance from light source, aquarium lid interference, and the height of the tank. A tall tank needs a stronger light to illuminate its bottom where the plants are grown, while a shorter tank does not.

Any type of light can be used to grow plants, as long as it has enough intensity. But we strongly recommend that you get an LED light, rather than a compact fluorescent (CF), fluorescent or another light technology. Nowadays most planted tank lights use LEDs because they can produce high brightness with lower power consumption and they do not need to be replaced very often. Some LED aquarium lights can be dimmable to adjust the light intensity for use in different tanks with different PAR requirements.

The intensity of light can vary based on the location it is measured in an aquarium.

Light Spread

Last, consider how far the light spreads. Aquarium lights usually have a 1-foot spread of light directly below them. This means that plants beyond that window won’t get as much sunlight and may not grow as well. On the other hand, a shop light has a huge light spread because it’s designed to light an entire room. (Just be aware that the color spectrum on a shop light may not show off the colors on your plants and fish as well.) If your aquarium is between 18 and 24 inches in width, you might need two aquarium lights, or one shop light. However, some manufacturers sell higher quality aquarium lights that boast a 120-degree light spread, which would cover more area than a generic brand light.

Depending on the size of your aquarium and the spread of your light, you may need multiple lamps to properly grow plants in all parts of the tank.

Which light is best for you?

Now that you have an understanding of the basics behind planted tank lighting, it’s clear that there is more to the story. You have many questions to answer.

What are your goals? Are you looking to grow your first aquascaping plants, make a profit from propagating plants, or participate in an international aquascaping contest? What types of plants would you like to grow? How much light intensity (or PAR) do they require? What are your aquarium’s dimensions and how many light bulbs do you need? – What are your financial limits and what light is most cost-effective?

You don’t have to spend a lot of money on a light that is efficient at growing low-light plants, if this is your first time getting into planted tanks. It may be worthwhile to consider the higher-priced options if you have birthday money. Higher quality lights last longer and are backed by extended warranties. These lights also have useful features such as the ability to dimm the light intensity and high water resistance, which allows them to withstand accidental drops in water.

You can find more information in our LED Aquarium Lighting guide. It will give you concrete recommendations on the best lights for your aquarium size.