Does Blue Light Cause Algae? In-depth Explanations 

Aquarium owners frequently add lights to their tanks to make them look more attractive and lively.

However, learning which light source is suitable for your fish and other plants in your aquarium is essential. 

Some may encourage the growth of unwanted vegetation or unfavorable environments for creatures. Does blue light cause algae? 

This post will show you in-depth explanations and helpful tips for choosing aquarium lights and controlling the growth of unwanted plants in your tank. 

Let’s scroll down!

Does Blue Light Cause Algae?

Due to its strong ability to promote plant growth, blue light is partially responsible for algae growth in your fish tank.

However, this lighting doesn’t generate extra heat. Your aquarium will be fine if you don’t leave the bulbs on throughout the day. 

You may want to know how blue light promotes algae development. Here are some detailed explanations. 

Blue light is beneficial to plant growth when penetrating water. Thus, it may promote the development of these plants if you can’t control them. 

Highly energized bulbs will support these unwanted plants to grow better since they can experience photosynthesis. 

On the other hand, blue light is one of the high-energy lighting sources with a spectrum between 380nm – 490nm that facilitates the photosynthesis process in plants. 

If you leave the blue light on for a long duration, like 10 – 12 hours per day, it may cause excess rapid algae expansion. 

However, installing the illumination system with a moonlight setting effect may not create a favorable environment for unwanted plants to grow. 

Blue light vs. algae overgrowth

What To Consider When Choosing Aquarium Light?

After knowing the unwanted effects of lighting on algae growth, it’s best to consider the following factors before installing these devices. 

Type Of Bulb

Several types of aquarium bulbs are available on the market. Here are some options you can install in your tank:

Halogen bulbs

Although they might be rather expensive, these bulbs offer intense illumination. Also, this type comes in various colors and produces a large amount of light. 

Fluorescent bulbs

These bulbs are among the most popular types. They are available in several colors, such as warm white, cool white, or daylight. 

These options are relatively affordable. Besides, they won’t generate too much heat like other types, making them good bulbs for aquariums. 

LED bulbs

This type has been increasingly popular as they require less energy than the above options while it has a longer lifespan. 

Moreover, LED bulbs offer various colors and different price ranges. Therefore, you can get the option that suits your needs and budget. 

Light Features

Some bulbs are outstanding with build dimmers and timers, making them beneficial for controlling algae development. 

Thanks to the dimmer, you can lower the illumination intensity that the bulb emits, which slows down the expansion of these plants.  

Besides, a timer allows you to set the light automatically to turn off during nighttime, reducing unwanted plants’ development. 

Light Wavelength

Different algae do not all grow well when exposed to the same types of bulbs. For instance, while green algae develop quickly in blue light, diatoms prefer red for healthy growth. 

It is crucial to pick a bulb that provides a range of wavelengths advantageous for the kind of algae you are trying to regulate.

Requirements Of Other Plants

You must also consider the illumination requirements of other tank inhabitants when selecting aquarium bulbs.

While more resilient aquarium plants may only require 5 watts per gallon, flowering aquarium vegetation might require 10 watts.

It’s necessary to consider the plants’ fertilizer and tank condition requirements. 

Considerations before buying light

How To Control Algae In Your Aquarium?

Algae overgrowth is an irritating issue for any aquarium. Therefore, you must find ways to control this problem. 

Here are some strategies to slow down and limit these plants from rapidly expanding in your tank:

Choose The Right Light

As you can see, many bulbs are available, so you should select suitable options for your tank. 

For instance, you can use compact LED, fluorescent, or standard fluorescent bulbs for your freshwater aquarium. 

These devices produce less heat, while they can reduce the growth of some unwanted plants. 

Moreover, it’s best to opt for devices with built-in dimmers and timers. Leave the bulbs on for 10 to 14 hours/day for your planted tank and 6 to 10 hours/day for aquariums with ornaments. 

Choose the right bulb.

Feed Your Fish Appropriately

Overfeeding is one of the leading causes of algal overgrowth and phosphate and ammonia pollution. These plants eat fish waste and leftover food. 

According to experienced aquarists, it’s best to feed your fish once every day or 2 to 3 times daily with small portions to avoid uneaten food.  

Feed your fish properly.

Change Water Regularly 

Water currents and rain dilute and wash away nitrate to avoid excessive build-up in the natural environment. 

However, in a closed system, you must regularly change the tank water to eliminate excess nutrients.  

If possible, you should perform 10 percent of the water every week. For a populated tank, changing 30 percent of the water every month is better. 

Change water regularly

Install Filtration System

Installing a filter helps prevent algae food from your tank, as it can control natural boosters and phosphate accumulation.

Here are some tips to choose the best-suited filter you may want to know:

Add Algae Eating Fish 

It’s a good idea to add some natural enemies of algae to your tanks, such as Plecos, Dwarf Otocinclus Catfish, and Cory Catfish. 

These creatures stay at the bottom of the aquarium and vacuum up leftover food or plant leaves before they get rotted, which produces toxic nitrite and ammonia. 

Cory Catfish


Do LED Lights Cause Algae Growth?

The short answer is no! These bulbs generate less heat, so if you don’t leave them on during the night, they won’t promote algae development. 

What Color Light Does Algae Not Like?

It’s the green light! It inefficiently absorbs the factors essential for photosynthesis, like carotenoids and chlorophyll A and B.

What Kind Of Light Does Not Grow Algae?

You can consider installing fluorescent lights for your aquarium to slow down the growth of unwanted plants. 

Are Fish Okay With LED Lights?

The good news is yes! These bulbs are suitable for fish as they produce less heat while offering low to medium illumination intensity.  

Will Algae Go Away On Its Own?

Yes! These plants will die off if they do not receive enough nutrients.

Final Thoughts

Does blue light cause algae? It may encourage these plants to grow if you leave the bulbs on throughout the day. 

Therefore, it’s best to select a suitable device for your aquarium and consider other factors like light wavelength and features. 

Hopefully, this post will be helpful for you. Thanks for reading!