Aquarium plant lighting is necessary for keeping water-based plants alive. Along with using them in fish tanks, these are also products we’d use in aquaponics farming.
In this article, we’ll go over the most important factors to consider when choosing aquarium plant lighting.
Aquarium Plant Lighting Guide
If you are a novice hobbyist looking for the right aquarium plant lighting, there are three main factors that you should consider:
- Spectrum
Comparing the lighting in a sterile health center and a serene coffee shop makes you understand how ‘white lights’ differ in terms of color temperature. This unit of measurement for this color temperature is called Kelvin (K). A warm, soft, and yellowish reading light might have a color temperature of close to 3,000K, while a white light with a tint of blue will have a rating of approximately 10,000K.
The truth is that aquarium plants can flourish in a wide range of color temperature ratings, which is why spectrum is not the most important factor. Usually, it comes down to your preference (most people do not like to look at excessively bright blue or red aquarium lights, for example). Many hobbyists tend to go with white, neutral aquarium plant lighting that stands at around 6,500K to 7,500K, because it is the closest thing to natural sunlight.
To put it simply, you can go for any spectrum except for something too blue (like the colors used to raise saltwater corals).
- Intensity
As far as aquarium plant lighting goes, brightness is one of the key things to consider. The intensity of your light will depend upon the type of plants that you plan to grow. Low-intensity aquarium plant lighting is suitable for things like ferns, crypts, anubias, and other similar undemanding species.
Medium lights, meanwhile, are good for all types of stem plants, as well as for many other species apart from carpeting plants. With a high-intensity light, you can grow pretty much anything. However, you will need to use CO2 (carbon dioxide) injections to manage the rapid plant growth and limit the production of algae. Due to the complexities associated with high-intensity lights, we encourage beginners to start off with low-intensity lighting, since the plants that fall in this category are some of the easiest and simplest species to grow.
Now, how do you decide how intense aquarium plant lighting actually is? The measure used to determine the intensity of aquarium lights is referred to as Photo-synthetically Active Radiation (PAR). The problem is that, since this rating can differ wildly depending upon the depth of an aquarium, manufacturers avoid publishing the PAR numbers for their aquarium lighting. A tall aquarium, for instance, will require a lot of light to target the bottom, while a shorter tank will require considerably less lighting to illuminate the base. Hence, the same light might be considered high-intensity for a 10-inch tank, but low-intensity for a 20-inch one.
If you have sufficient aquarium plant lighting intensity, the brand or type will not matter much. Having said that, we do recommend preferring LED lighting over other light technologies like fluorescent or CF (Compact Fluorescent). LED is the best choice because it can produce stronger lighting while using lower power. In addition, LED lights are durable and do not need to be replaced often. Besides, you can even find dimmable LED aquarium lights, which means that you can control the lighting intensity and use the lights for multiple aquariums with differing PAR requirements.
- Spread
The third factor to consider is the extent of the aquarium plant lighting’s spread or dispersion. Generally, aquarium plant lighting will spread around one foot directly below them, which means that plants beyond that range will receive considerably less light and might not grow as well as the plants within the one-foot window. Shop lights, on the other hand, offer large spreads since they are designed to light up entire rooms. So, for an aquarium that is around 20 to 24 inches wide, a single cheap shop light or a couple of aquarium lights should do nicely.
Are Aquarium Lights Good for Plants?
Yes, aquarium plant lighting emits a unique blue light that encourages green and lush growth for your plants. However, if you are looking to grow flowers on your houseplant, you need to supplement the light source from a light that is towards the ‘red’ end of the lighting spectrum. An incandescent bulb can be a good and convenient source of red light for plants.
Check out this video to understand a bit more about choosing the correct lights.
Which Color Light is Best for a Planted Aquarium?
It is essential that your aquarium plants get the right amount and type of light. As a rule of thumb, plants that are bright green will prefer brighter lights, while those that are dull green will thrive in less light.
Aquarium Plant Lighting Requirements
- Schedule
When it comes to aquarium plant lighting, more is not necessarily better. In other words, keeping the lights on at all times can actually be detrimental to your plants. To ensure your plants’ optimal health, you need to know when to switch on and switch off the lights.
Ideally, you should set a timer system up; as it will ensure that your plants get an equal amount of light every day. Make sure that your daily lighting period does not exceed eight hours. Going beyond eight hours will not just scorch your plants but also encourage algae growth and, all in all, is a recipe for disaster.
It is important to find the right balance between lighting, fertilizer, and CO2.
- Light Intensity
As discussed earlier, there is no easy way to answer the question, ‘how much aquarium light is enough?’ since this will be determined by the type of lighting as well as the structure of your tank. Having said that, there are some general guidelines in this regard that you can adhere to.
Some gardeners consider the wattage-to- water volume ratio to determine if the lighting is sufficient for their plants. In general, this ratio should be:
| Required Intensity | Recommended Wattage-to-Water Volume Ratio |
| Low | Around 0.25 |
| Medium/moderate | Around 0.50 |
| High | At least 0.8 |
An alternative measurement for this purpose is ‘lumen’, which is a unit that is used to measure the amount of light that a particular light source is giving off. In general, lumen is a more accurate indicator relative to watts.
| Required Intensity | Recommended Lumen per Liter: |
| Low | Between 15 and 25 |
| Medium/moderate | Between 25 and 50 |
| High | At least 50 |
The problem is, although lumen is better than wattage, neither of the two is a good measure for required light intensity. Wattage is a measure of the electricity production and not the output, which is why it is obsolete. Lumen, meanwhile, considers the human-eye sensitivities to the light spectrum, which means that it is also not completely objective.
This is where PAR comes into the picture, and provides the amount of light required for proper photosynthesis. In general, the PAR guidelines followed by the community are as follows:
| Required Intensity | Recommended PAR |
| Low | Between 75 and 100 µ |
| Medium/moderate | Approximately 150 µ |
| High | At least 200 µ |
- Color Spectrum
Even though plants use all the spectrum colors for photosynthesis, a blue/red spectrum offers better contrast, stimulating coloration and greater pigmentation.
Hence, the goal should be to highlight the red and blue lights, without disrupting the overall balance of the spectrum. According to experts, the red light should take up at least 50% of the spectrum, while blue should be limited to 15%. This is because plants can soak up around 75% of the total red light offered to them, but blue light is only needed in a limited number of internal processes.
The remainder of the spectrum can be balanced by colors like orange.
- Visually Enhancing
Lights, through color temperature, can have an impact on the color of your plants. Like we mentioned, the Kelvin (K) reading will affect the hues and shades that your plants give off. The color temperature, therefore, influences the degree of clarity in the plants’ natural colors. If you use a light source that has a high Color Rendering Index (CRI), you can expect topnotch color recognition.
Make sure to choose lights with the right color temperatures; the proper temperatures can make your plants look more natural and visually appealing.
Can Aquarium Plants Grow in Blue LED Lights?
Aquarium plants make use of a very specific kind of blue light. This blue light is called actinic blue, and promotes the growth of the stem and the leaves of the plants. In other words, not only is blue light fine for your aquarium plants, it is essential for their growth and prosperity.
Do Fish Like Blue Light At Night?
No, fish do not like blue light at night. In fact, we strongly recommend you to NOT keep any colored lights (blue or otherwise) on in the aquarium during night. Fish – unless they are nocturnal – rely upon light cycles for the maintenance of their sleep cycles. This means that leaving lights on at night will affect the fishes’ quality of sleep, and cause them to become stressed and sleep-deprived, impacting their short- and long-term health.
Final Thoughts on Aquarium Plant Lighting
To sum up, the spread, intensity, and lighting are the three most important factors to consider when choosing aquarium plant lighting. It is also important that you implement the right lighting schedule and color spectrum. We hope that this guide will help you make the right aquarium lighting choice for your plants.
