How to Pick the Best Planted Aquarium Light

We get asked a lot of questions about lighting. Let’s discuss three lighting options and their implications for beginners to help you get started with your planted tank journey.

#1 Color Spectrum

You’ve probably seen the difference in lighting between a cozy coffee shop and a hospital. This is known as “white” light. Its color temperature is measured in Kelvin (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. Many hobbyists like to use a neutral white light around 5000 to 6500 K because it’s said to best simulate natural daylight. You can use any light spectrum, as long as it is not too blue (such a light used to raise 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 lights (or low-intensity lights) can grow anubias, cryptocoryne (or crypts), ferns, and other undemanding plants. Medium lighting is good for most species, except those that require 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). 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 requires a stronger light to illuminate the bottom of the tank where the plants are growing, whereas a short tank does not.

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. Because they are brighter and require less power, LEDs are the most popular choice for planted tank lights. You can also dim the lights to suit different tank PAR requirements.

The intensity of a light varies a lot depending on where you are measuring it in the aquarium.

Light Spread

Last, consider how far the light spreads. The majority of aquarium lights have a 1 foot light spread below them. This means plants that aren’t in that area won’t receive as much light, and possibly won’t grow 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.) So, if your aquarium is 18 to 24 inches wide, you may need to buy two aquarium lights or use one cheap 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 and spread of your light source, you might need several lamps to grow plants in every part of the aquarium.

Which Light Is Right 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 kind of plants do you want to grow, and how much light intensity or PAR do they require? – What are the dimensions of the aquarium, and how many lights do you need to cover it? – What is your budget, and which light will get you the most bang for your buck?

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. 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.