Why Does Aquarium Gravel Turns Green? (How To Clean It?)

Image of an aquarium with green gravel

You can use different types of gravel to make an aquarium look appealing. However, you may find the gravel turning green after a while. So, why does aquarium gravel turns green?

Aquarium gravel usually turns green due to green algae bloom. Green algae are caused by excessive lighting, poor water quality, and increased nitrate and phosphate levels of the tank water. You can control green algae by avoiding overfeeding, controlling lighting, and performing regular maintenance.

Green algae in moderation are natural and even healthy in aquariums. However, excess green algae growth can harm fish and plants. So, let’s talk about this in detail now.

Causes Of Green Algae Overgrowth In An Aquarium

Green algae, also popularly known as spot, thread, or hair algae, are natural in many fish tanks. These algae thrive in an environment that’s rich in light, water, and nutrients.

Given below are the various reasons for green algae overgrowth in an aquarium:

  • Lack of proper tank maintenance is the most common reason for green algae overgrowth.
  • Excessive exposure of the aquarium to direct sunlight or artificial lighting can result in a green algae bloom.
  • Overstocking of fish leads to excess fish waste. This increases the ammonia levels of the tank water, which provides additional nutrition for green algae.
  • Irregular water changes can also result in green algae growth.
  • Overfeeding fish is another reason for green algae overgrowth. Overfeeding results in uneaten food that ultimately decays in the tank water. The decayed matter provides excess nutrients to the green algae.
  • High nitrate and phosphate levels in the tank water also cause an overgrowth of green algae.

How To Clean Green Algae From Gravel?

You can clean green algae from the gravel by using a soft brush and water. However, the best way to remove them is by vacuuming the gravel.

An aquarium siphon, also known as a gravel vacuum, helps turn over the gravel and eliminate the green algae by depriving them of light.

Vacuuming also helps remove the debris and other wastes from the gravel that act as sources of nutrients for green algae.

The other option to remove green algae from the gravel is bleaching. The bleach-to-water ratio should be one-quarter teaspoon per gallon of water in the tank. You can then spray the solution on the gravel.

Bleaching is the most efficient way to get rid of green algae and other unwanted organisms from the gravel that may be lurking in the tank.

While using bleach, don’t ever mix it with any other chemical. Also, don’t use bleach in a concentration higher than 10%.

If bleach is used in higher concentrations or with other chemicals, it can be hazardous to the tank inhabitants.

Recommended Further Reading:

6 Ways To Control Green Algae Growth In Aquariums

Green algae are the most common algae in many fish tanks. However, the good thing is that they can be kept under control if the tank is well-cared.

Given below are some ways to control green algae growth in an aquarium.

1. Decrease the tank lighting.

Most algae, including green algae, grow because of excessive lightning. In particular, sunlight accelerates green algae growth. So it’s advisable not to place the tank near a window with direct access to sunlight.

Also, if you are using artificial lighting, limit the intensity of the lighting. You can keep the lights on for about 8 to 10 hours for planted tanks. Whereas for unplanted tanks, lightning of 7 to 8 hours a day is sufficient.

Usage of a timer is the most effective way to ensure lighting is kept on for an optimal time.

2. Introduce algae eaters in the tank.

The introduction of algae eaters is another way to control algae overgrowth in an aquarium.

Nerite snails eat green algae. So they can help keep the tank algae-free. However, nerite snails can’t eliminate green algae altogether as they are very slow in eating the algae.

Siamese algae eaters and Amano shrimp are some other algae eaters that enjoy eating green algae.

When you introduce an algae eater in the tank, make sure they are compatible with the tank inhabitants.

3. Increase plants in the aquarium.

Live plants need the same nutrients that algae need to thrive. Hence, the addition of plants is an excellent way to control algae growth.

Since plants compete directly with algae for the nutrients and absorb most of them, there will be very few nutrients left for the algae.

Fewer nutrients mean there’s less chance of algal proliferation.

Related Further Reading:

4. Avoid overfeeding the fish.

Overfeeding the fish leads to increased ammonia and phosphates in the tank water on which green algae feed. So you must remove any uneaten fish food promptly to maintain the water quality.

Also, feed the fish only once or twice a day. The quantity of food should be whatever they can eat in about 3 to 5 minutes.

5. Perform regular maintenance of the tank.

Regular maintenance of the tank is another great way to control green algae bloom. Periodical water change is essential to maintain any fish tank.

While it’s unnecessary to perform a complete water change every time, you need to do at least a partial water change of 10% to 15% every week to ensure the nutrient levels are balanced.

This will assist in removing the excess waste that algae feed on and will go a long way in controlling green algae overgrowth.

Besides, regular cleaning of aquarium filters, equipment, decorations, and glass is equally important.

6. Test the water source.

Testing the water source can help identify whether the problem lies within the aquarium or outside it. For example, tap water often contains fertilizers like phosphates and nitrates that promote green algae bloom.

If these fertilizers are present in the tap water, it’s better to use a phosphate remover or filtered water for the aquarium.

Also, chemicals are readily available at most pet stores that help reduce some of the additives in the aquarium water.

Interesting Further Reading:

Are Green Algae Good For Fish?

Green algae are good for fish as long as their growth is under control. They are considered to be good algae as they are a dietary source for many fish species.

However, if there is a green alga bloom in an aquarium, it can deprive the fish of the essential nutrients and prove detrimental to their overall growth.

Moreover, a green algae bloom can also make the aquarium water green and murky.

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