How to Pick the Best Planted Aquarium Light

One of the most common questions we get asked is “What light should I get for my planted aquarium?” The short answer is that it depends. 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.

The fact that aquarium plants can thrive in a wide range Kelvin levels doesn’t make a difference to their color spectrum is a truth. Because we don’t like to see aquarium lights that are too bright or too dim, it comes down to personal preference. A neutral white light between 5000 and 6500 K is preferred by many hobbyists as it best mimics natural daylight. Simply speaking, you can choose a light with just about any color spectrum as long as it’s not too blue (such as those used for raising 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 of a light should you get? It depends on the type of aquarium plants that you are trying to grow. Low lights (or low-intensity lights) can grow anubias, cryptocoryne (or crypts), ferns, and other undemanding plants. Medium lights are good for stem plants and most other species except for demanding carpeting plants. High light can grow almost anything but requires carbon dioxide (CO2) injection to maintain a fast growth rate and minimize the risk of 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). Most manufacturers do not publish their PAR numbers. This rating is affected by distance from the light source, tank height, interference from the aquarium lid and plant placement. A tall tank will require a stronger light source to illuminate the bottom of its tank, where the plants are growing. A shorter tank doesn’t.

As long as there is enough light intensity, you can grow plants with any kind of light. However, we recommend an LED light over fluorescent, compact fluorescent (CF) or other types of light. Most LED-based planted tank lights are now made from LEDs. They can provide high brightness and low power consumption, so they don’t need to be changed as often. Plus, some LED aquarium lights are dimmable, allowing you to control the light intensity in case you want to use them for different tanks that have different PAR requirements.

Depending on the place you measure it in an aquarium, the intensity of a light will vary.

Light Spread

Last, consider how far the light spreads. Most aquarium lights have a good 1-foot light spread directly below them, meaning that plants outside of that window won’t get as much light and potentially won’t grow as well. A shop light, on the other hand has a large light spread since it is designed to light a whole 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.) You may need to purchase two aquarium lights if your aquarium measures 18-24 inches in diameter. Some aquarium lights are better quality and have a 120-degree spread of light, so they cover more space than generic brands.

Depending on the size and spread of your light source, you might need several lamps to grow plants in every part of the aquarium.

Which light is best for you?

Now that you know the basics of planted tank lighting, you know that the answer isn’t that simple. There are several questions you need to answer for yourself:

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 the dimensions of your aquarium and how many lights will you need? – What are your financial limits and what light is most cost-effective?

It’s okay to choose a low-cost light source that can grow low-light plants if you’re just starting out with planted tanks. If you have extra birthday money, it might be worth looking into the more expensive options. Higher quality lights last longer and are backed by extended warranties. These lights have many useful features like dimming the light intensity, and high water resistance so they can withstand being dropped 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.