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 soft, warm reading light that gives everything a yellowish glow may have a rating of 2700K, whereas a cool white light with a bluish tint may 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. 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 of a light should you get? First off, it depends on what kind of aquarium plants you want 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 lighting is good for most species, except those that require 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. We recommend that you start with low-light plants because they are the most difficult and beginner-friendly of all the 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 Most manufacturers do not publish their PAR numbers.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

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. 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.) You may need to purchase two aquarium lights if your aquarium measures 18-24 inches in diameter. 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 best for you?

You now know the basics of plant tank lighting. But it is not that easy. There are several questions you need to answer for yourself:

What are your goals? Are you trying to grow your first aquarium plants, propagate plants for a profit, or win an international aquascaping competition? 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?

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. These higher quality lights tend to last much longer and have extended warranties backed by the manufacturers. These lights have many useful features like dimming the light intensity, and high water resistance so they can withstand being 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.