How to Pick the Best Planted Aquarium Light
We get asked a lot of questions about lighting. To help you get started on your planted tank journey, let’s talk about three different lighting parameters and what they mean for beginner hobbyists.
#1 Color Spectrum
If you’ve ever looked at the lighting in a cozy coffee shop versus a sterile hospital, you know that “white” lights all vary in color temperature, which is measured in units of Kelvin (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.
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. Because it is said to best replicate natural daylight, many hobbyists prefer to use a neutral white light from 5000 to 6500K. 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 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 lights are good for stem plants and most other species except for demanding carpeting plants. High-lights can grow nearly anything but require CO2 injection to keep up with fast plant growth. 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 or high light?” Plant growing lights are often measured in PAR (or Photosynthetically active radiation). However, most manufacturers don’t publish their PAR numbers because this rating differs drastically depending on the distance from the light, height of the tank, interference from the aquarium lid, and placement of the plants. A tall tank needs a stronger light to illuminate its bottom where the plants are grown, while a shorter tank does not.
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. 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
You should also consider the spread or dispersal of light. 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. 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.) So, if your aquarium is 18 to 24 inches wide, you may need to buy two aquarium lights or use one cheap shop light. You can find better quality aquarium lights from reputable manufacturers that have a 120-degree beam of light. This will cover more space 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. 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 type of plants are you looking to grow and what level of light intensity do they need? – 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?
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.
For more information, check out our LED Aquarium Lighting Guide for concrete suggestions on which lights to get based on your aquarium size.