How to Pick the Best Planted Aquarium Light

We get asked a lot of questions about lighting. Let’s take a look at three lighting options to help you get started in your plant 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 soft, warm light that gives everything a yellowish glow could have a rating at 2700K. On the other hand, a cool, white light with a bluish tint could be labeled as 10,000K.

It doesn’t really matter what color spectrum you use to grow aquarium plants. They can thrive in any Kelvin range. 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. 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? It all depends on the kind of aquarium plant you wish to grow. Low lighting (or low-intensity light) is good for anubias, cryptocoryne or crypts, ferns, as well as other plants that are not demanding. Medium lights are good for stem plants and most other species except for demanding 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. Because of the complexities that come with high light planted aquariums, we recommend that most people start with growing low light plants since they’re some of the hardiest, most beginner-friendly species.

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 Most manufacturers do not publish their PAR numbers.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.

You can use almost any type or brand of light to grow plants as long as you have enough light intensity, but we highly recommend getting an LED light – rather than fluorescent, compact fluorescent (CF), or other light technology. 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. Some LED aquarium lights can be dimmable to adjust the light intensity for use in different tanks with different PAR requirements.

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

Light Spread

The final category to consider is how far the light spreads or disperses. 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. Shop lights, however, have a wider light spread as they are designed to light entire rooms. (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.

It depends on how large your tank is and how bright the light spreads, so you might need more lamps to properly grow plants in each part.

Which Light Is Right 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 you trying accomplish? Are you trying to grow your first aquarium plants, propagate plants for a profit, or win an international aquascaping competition? What type of plants are you looking to grow and what level of light intensity do they need? What are your aquarium’s dimensions and how many light bulbs do you need? – How much money do you have to spend on lighting? Which light is the best for you?

If you’re first getting into planted tanks, there’s nothing wrong with choosing a cost-effective light that does well at growing low light plants. It may be worthwhile to consider the higher-priced options if you have birthday money. The higher quality lights are more durable and come with extended warranties. They also come with useful features, like the ability to dim the light intensity or high water resistance to survive being accidentally dropped in water.

Check out our LED Aquarium Lighting Manual for more information and concrete suggestions on what lights you should get based upon your aquarium’s size.