Best Light Spectrum for Aquarium Plants

Aquarium plants are a great addition to any fish tank. They add to the aesthetics as well as provide your fish with a healthy, stimulating environment.

Most importantly, they prevent the buildup of algae that can be harmful to your fish and detrimental to the aquarium.

Aquatic plants also soak up the nitrates and phosphates in the tank, thus maintaining the aquarium’s balance.

However, with these aesthetically pleasing plants comes some responsibility to ensure they grow in a healthy environment.

In addition to special fertilizers, water conditions, and a substrate, they require appropriate aquatic plant lighting.

Why Aquarium Plants Need Good Lighting

Like all other plants, aquatic plants require adequate light for photosynthesis. Without enough good lighting, their health and growth will be compromised.

Proper lighting allows the plants in the aquatic setup to efficiently absorb the carbon dioxide gas breathed out by your fish.

If there’s too much light, microscopic floating algae will start to grow in your fish tank. And soon, the water in the tank will turn green. Needless to say, it will eat up the aesthetics of your aquarium.

The right level of light will cause some green algae spots to form on the sides of the aquarium and the surface of the rocks.

Don’t worry when your fish nibbles on The algae, as that’s normal and there are many fishes that eat algae as a part of their diet. It will also make your aquarium look like a healthy community fish tank.

If your fish tank is placed near a window from where direct sunlight comes in, the aquatic plants may need no more than five hours of artificial lighting.

However, you must make sure that sunlight doesn’t fall on the tank directly, as it may cause the algae growth to get out of control.

Ideally, artificial lighting should be present for at least eight hours a day. You can keep it on for 10-12 hours if need be. This is because natural light may not be enough for aquatic plants to reach their full potential.

You must select an appropriate light spectrum for your fish tank, which allows the plants to grow in a healthy way.

If you’re a beginner or a new aquarium owner, it’s natural to get overwhelmed by the full range of aquatic plant lighting available out there.

We’ll tell you all about it, but first, let’s discuss what a light spectrum really is.

What is a Light Spectrum?

Light is an electromagnetic wave. The colors that you see as well as those that are invisible to the naked human eye have a particular wavelength. This is why you can differentiate one color from another.

Hence, light has a band of colors or ‘spectrum’ that goes from very high energy, short-wavelength radiation to very low energy, long-wavelength radiation. The colors of the light that we can see fall (i.e., the visible light wavelength) somewhere in the middle of this spectrum.

That being said, artificial light and LED light fixtures (light bulb) all have unique wavelengths of light. You will get some wavelengths more from one light source than from others.

You may have seen some light bulbs that give out bright blue light while others give out white light by balancing all the colors.

The same goes for aquarium lighting. You can check the output light spectrum on the packaging or website.

The spectrum of the light will significantly affect your aquatic plants’ response to the new lighting. This is why it is crucial to determine the best light spectrum for your aquarium plants.

What about Color Temperature?

Checking the color temperature of the aquarium lighting is an easy way to identify its light spectrum. Color temperature is also referred to as Kelvin rating.

Without getting into the technical details, let’s just tell you that the color temperature of yellow lights tends to be less than 3,000 K, whereas bluish light may have a color temperature of more than 5,000 K.

The Kelvin rating of natural environment sunlight is believed to be approximately 5,700 K, so some people suggest using aquarium lighting with a similar color temperature for best results.

However, there are a few other factors that you must keep in mind when choosing the best light spectrum for aquarium plants.

Other Things You Should Focus on

Apart from the color temperature of the aquarium lighting, you need to look at the Photosynthetic Active Radiation and Photosynthetic Action Spectrum.

Photosynthetic Active Radiation (PAR)

PAR (photosynthetically active radiation) refers to the light intensity in the spectrum band. It ranges from 300 nm to 700 nm. Aquatic plants and corals rely on PAR for their growth and health.

This reading determines the amount of light energy available for your aquarium plants to feed on.

You can measure the PAR reading of the aquarium lighting by putting a PAR meter in the fish tank.

Alternatively, you can have an aquarium expert do it for you. Generally, you should look for high PAR reading because the higher it is, the more chances of your aquatic plants’ growth.

That being said, it’s not smart to rely solely on PAR numbers for determining the efficiency of a particular light spectrum.

Photosynthetic Active Spectrum (PAS)

PAS is a more reliable indicator of light efficiency.

It focuses on specific wavelengths of the aquarium lighting that stimulate chlorophyll A and chlorophyll B in plants. These elements play an integral role in activating the plant’s growth.

When it comes to PAS, generalizations don’t work well. Each aquatic plant has its own PAS wavelength, so you need to think beforehand about the type of plant you want to place in your fish tank along with its PAS requirements.

What is the Best Light Spectrum for Aquarium Plants?

When it comes to choosing the best light spectrum for aquarium plants, there’s no one-size-fits-all solution.

The ideal option will depend on the type of aquatic plants and fish species you have in the tank and their unique lighting needs and requirements.

Nevertheless, there are a few good rules of thumb you can follow.

It is said that the aquarium plants use some percentage of the light during photosynthesis while another percentage goes to waste. This refers to the relative quantum efficiency of a particular wavelength of light.

Scientists believe that plants use a much higher percentage of the red light for photosynthesis as compared to blue light. The high energy content of blue light is not suitable for the internal chemical processes taking place in the cells of the plants, so a lot of it ends up going to waste.

Aquarium plants may be able to use up to 75% of the incident red light. This makes it a top choice for aquarists like you. You also have the option of green light, which falls somewhere between the red and blue light.

Aquarium experts recommend you have a minimum of 50% red light and no more than 15% of blue light in your spectrum.

With this composition, you should be able to give your aquarium plants a stimulating environment to grow in a stable manner, given that other crucial factors are also taken care of.

Let’s also tell you that the depth of your fish tank affects the absorption of different wavelengths of light. Hence, make sure you position your aquatic plants accordingly.

While this information will ensure the proper growth of aquatic plants in most species, each plant has unique needs and may react differently to light.

Therefore, before choosing the best light spectrum for aquarium plants, you must research the specific needs and lighting requirements of your particular plant species.

In addition to this, find out which other aquatic plants they work well with and how much hours of light is enough for them.

This little effort will help you set your timer, making it easier for you to take care of aquarium plants.

Let’s dive in to discover which aquatic plants you should consider placing in your fish tank.

For Beginners and Novices

If you’re a beginner, you’re better off with aquatic plants that are easy to grow and take care of.

These plants are hardy and can grow under almost all kinds of lighting conditions. Even if you don’t have much knowledge about them, you’ll be good to go.

Such plants don’t require much attention or care and thus, there are no chances of them dying unexpectedly.

The plants that fall into this category include java moss, java fern, guppy grass, anubias, and hornwort.

All these species thrive in low light environments, provided that they receive an adequate amount of backdrop and color. With these aquatic plants in your fish tank, you won’t have to worry about keeping the tank’s ecosystem healthy.

You can easily find beginner-friendly plants for your aquarium in physical shops or online.

For Experienced Aquarist

If you’re an advanced aquarist who wants to keep things exciting, you should consider going for aquatic plants that demand a specific light intensity and color of light to grow healthily.

The plants in this group won’t survive without optimal conditions.

A few examples of demanding aquarium plants include baby tears and dwarf hair-grass.

These plant species undoubtedly look stunning in full bloom. However, you would have to ensure that you have the time, dedication, and resources to put in the extra effort to take proper care of them.

The Bottom Line

There’s no definite answer to the question of what is the best light spectrum for aquarium plants.

Factors like the types of aquatic plants you want, your budget, and your future plans of expanding the fish tank will help you determine the ideal option.

Keep in mind that different lighting options cater to the needs of aquariums of different sizes. Also, research is the key to making a smart decision.

The time you spend evaluating various options today will be worth it when you see your aquatic plants thriving in a clean and healthy tank!

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