How Long Should You Leave a Aquarium Lights On?

How Long Should You Leave a Aquarium Lights On?

Fish keeping, is not a random thing. You do not just get a fish and place it in an aquarium leaving it to survive on its own. Very high temperatures or too low temperatures for the fish, it will get ill which will can ultimately lead to death.

If you do not have the right water filter to clean the water tank or the aquarium, the fish might get stressed due to poor living conditions which can also lead to death. Too much feeding is not advised and too little of it will result to your fish being weak and malnutrition.

Too much light or too little of it, the fish will also get stressed, affect its eating which can result to death. Therefore, as you can see, fish keeping, whether as a pet or for business, is strategic.

Before getting any type of fish to keep in your aquarium or water tank, you will need to do a thorough research and seek advice from professionals in order to understand the fish’s living conditions requirements. To help you keep your fish with proper lighting, we shall discuss how long you should leave your fish tank lights on, and everything that you need to know about aquarium lighting.

Aquarium lighting is both a necessity for the survival of your fish, and also a design feature to enhance the beauty of the aquarium. Both the fish and the plants in the aquarium need the light to thrive, while the light’s soft illumination makes it an important piece of room decor.

However, getting to know how much light the plants and the fish need, and for how long in a day they will need the light can be a hard decision to make.

Generally, most aquariums need about 8-12 hours of lighting each day. Thought, this number really depends on the types of plants and fish species you keep in the aquarium.

To determine just how long light your aquarium will need depends on a number of factors:

  • The species of fish in your aquarium
  • The total number and type of live aquatic plants in the aquarium
  • The amount of natural light that is already in the room
  • The level of algae in the aquarium

Light Requirement for Different Fish Species

Every type of fish is taken from its natural habitat. Therefore, the amount of lighting to be provided in the aquarium will be determined by the natural setting and native environments of the fish.

For instance tropical fish species get around 12 hours of lighting each day, therefore logic suggests they will also need 12 hours of lighting each day to replicate their natural environment. This lighting can be both from the natural source and by the use of supplemental aquarium lighting.

goldfishA few species such as the cichlids survive best in low lit environments. Too much supplemental lighting for these types of fish in the aquarium may affect them negatively. Other types of species such as goldfish, ricefish, and zebrafish, from the cold water regions, experience different amount of light each day depending with the season.

Therefore, for these types of fish, you can create a more natural environmental setting by varying the length of aquarium lighting depending with the current season.

However, aquarium lighting is more about you and not the fish. Lighting levels in the aquarium does not have major effects on the fish all that much. You need lighting in the aquarium so that you are able to see and enjoy your fish.

The nature of the aquarium, small container with four glass walls, permits more light to the fish than they receive in their native environments, whether you use supplemental lights or not. Most species of fish do not mind getting more light in the aquarium.

Light Requirement for Different Aquatic Plants

Different Plants Have Different Light Requirements

Different Plants Have Different Light Requirements

Fish is not the only thing needing light to thrive in the aquarium, the aquatic plants also need light too. Plants need light to perform their necessary photosynthesis. Similar to plants on the ground, aquatic plants also need light to synthesize food from water and carbon dioxide.

The plants will need both the light from the natural room light and from the added aquarium lighting.

Plants need at least 8 hours of lighting each day. Therefore if you have aquatic plants, you will need supplemental lighting to ensure there is constant lighting within the half day.

However, the exact amount of light will depend on the setup of the room and placement of the aquarium to room temperatures and the type of your aquatic plant. On the other hand, if you do not have any aquatic plant, you will only need as much light as the fish needs.

While choosing the type of aquatic plants to keep in the aquarium, it is recommended that you choose plants that will match with the type of fish in the aquarium. For instance tropical fish should also get tropical plants and cold temperature water plants be matched with cold water fish species.

Most tropical plants will do well with 12 hours of lighting each day all year long. These are amazon sword, java fern, banana plant, anubias and others. Cold water plants will need light levels determined by seasons (tiger lotus). Some cold water plants will die off in cold season, even if you provide enough light and stable temperature.

It is important to note, during the early days of plant development in the aquarium, you will need to leave the lights on for longer periods, to allow the roots of the plant to grow stronger and deeper.

If is also important to know, that too much light will also promote algae growth. I will explain this below.

Amount of Ambient Lighting

The total amount of hours to leave the aquarium lights on will also depend on the amount of ambient light allowed into the room.

If your aquarium is placed in a position where it is receiving direct sunlight, or your room has big windows that allow natural light in the house, or your aquarium is placed in a room where lamps are always on, most likely you will not need to run the supplement lighting throughout the day.

You will be required to switch on the aquatic lights a few hours in the day, especially late in the evenings because ambient room lighting is not direct.

During the cold seasons such as winter, when natural light levels are low, leave the aquatic lightings on for longer.

This will enhance the growth of healthier aquatic plants. However, as the hours of the day lengthen, shorten the lighting period to offer only the correct amount of light required in the aquarium.

Too Much Algae Growth

Too Much Light Promotes Algae Growth

Too Much Light Promotes Algae Growth

Algae are tiny aquatic plants. Their growth and presence in the aquarium is mostly facilitated and highly promoted by too much light.

If your aquarium is prone to developing high levels of algae, then consider reducing the time you leave the aquarium lights on to 8 hours or less in a day, in order to limit algae growth.

Monitoring algae levels in the aquarium, is therefore, a good way to determine how long you should leave the lights on in the tank. However, remember the ultimate goal is not to eliminate all the algae in the aquarium. Some fish species depend on algae as a source of food, therefore the goal is to maintain its growth manageable levels.

Direct sunlight promotes a faster growth of algae compared to artificial light. Therefore, an aquarium that is placed near direct sunlight, for instance close to the window, will require less artificial lighting compared to one in a darker room.

Controlling Aquarium Lighting

Most people find it hard to control and maintain uniform periods of lighting in the aquarium same time each day. One could forget to turn on or off the aquarium lights, or get too busy at work.

Luckily, there are on-off timers available in the market that you can set to automatically switch the lights on and off after a period of time that you have set. These timers are easily available at any pet store at an affordable price. Every aquarium owner is advised to have one.

Do Aquarium Lights Generate Heat?

Aquarium lights not only provide light for your fish and aquatic plants, but also produce heat that can significantly raise the temperature levels of water in the aquarium.

Some of the lightings types that can produce a lot of heat, enough heat to kill fish in small aquariums, include metal halide incandescent and VHO-Fluorescent. Make sure you do not leave these types lights on overnight to avoid accidents.

If you want safer and mild lightings, consider getting standard fluorescent lights. You can leave them on overnight without any potential danger.

Since light can have a major effect on the well-being of your fish, increase temperature levels or cause algae to grow in high levels, it is very important to monitor and control the time limit that you leave the lights on in the tank. Get an automatic on-off timer to help you switch the lights on and off after a period of time.

Written by Fabian

Hey, I'm Fabian, chief editor at Aquarium Nexus. I really enjoy the aquarium hobby and love sharing my experience with others. If you have any questions feel free to contact me or leave a comment below.

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