Why Is Your Aquarium Gravel Turning Yellow? (How To Fix It?)

Image of an aquarium with yellow gravel

You may suddenly notice a yellow tint on your aquarium gravel that reduces its attractiveness. So, why is your aquarium gravel turning yellow?

Aquarium gravel can turn yellow due to yellow algae, tannins leaking from driftwood, rotting plants, debris, leftover food, and fish waste. However, you can fix and prevent it by performing regular water changes, maintaining water quality, removing floating debris, and installing aquarium filters.

Okay! Let’s now understand the various reasons why your aquarium gravel is turning yellow.

5 Main Reasons Why Aquarium Gravel Turns Yellow?

Aquarium gravel facilitates the filtration of waste and supports the growth of beneficial bacteria.

However, a yellowish color in the aquarium water indicates that the gravel or substrate can’t filter the waste and needs further investigation.

Given below are the five main reasons why aquarium gravel turns yellow.

1. Algae or bacterial bloom.

Yellow algae, also known as mustard algae, is a type of green algae that grows on rocks and other surfaces submerged underwater.

Microorganisms like algae thrive on waste and can taint the water and gravel inside the aquarium. Therefore, the gravel and water can look yellow. In addition, they can deteriorate the water quality and create an unpleasant odor.

Bacterial bloom can occur when your tank is not clean or is exposed to bacteria that alter the water quality. Both algae and bacteria can affect the aquarium gravel and water, making them look cloudy and yellow.

2. Tannins.

Tannins are not considered harmful to aquarium inhabitants as they are natural compounds found in plants. Tannins are a brownish or yellowish, bitter-tasting organic substance found in barks and plant tissues.

However, if tannins leak from the driftwood and plants in the aquarium, they can turn the water and gravel yellow. Moreover, the discoloring of the water can lower the pH of the aquarium water.

So fish that prefer alkaline conditions can get stressed if the tannins make the water acidic. Besides discoloration of aquarium gravel and water, tannins can impact the overall balance of the aquarium.

3. Decaying plants.

Another reason for aquarium gravel to turn yellow is decaying plants and organic matter. In a planted aquarium, stray leaves can separate from aquatic plants and float in the tank water.

In the absence of proper nutrition, the aquatic plants will start to wilt. Uncleaned rotting plants and debris look harmless but can build up ammonia and pollute the aquarium water.

Ammonia turns into nitrite, and a high concentration of nitrite levels can be toxic to the fish. So decaying plants not only damage the aesthetics of the aquarium but can also be a potential hazard for your aquatic pets.

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4. Unwashed substrate.

Adding unwashed substrate can turn the aquarium water yellow. If the gravel or sand added to the aquarium contains tiny particles of dust and accumulated debris, it will make the aquarium look hazy and yellow.

In addition to dust and debris, specific substrates can also contain tannins that can discolor the gravel and the aquarium water.

5. Leftover food and fish waste.

Uneaten fish food starts to rot inside the tank. As a result, it increases the nitrate and phosphate levels of the tank water.

On the other hand, fish waste can increase due to overfeeding or overstocking of fish. The fish poop will make the water murky and build up ammonia levels in the aquarium.

Leftover food and fish waste pollute the gravel and water, increase the ammonia or nitrite levels, and reduce the oxygen concentration. This can push the fish to the surface gasping for air, which can be fatal to them.

Let’s now understand how you can fix and avoid the aquarium gravel from turning yellow.

How To Fix And Prevent Yellow Aquarium Gravel?

Given below are some measures that you can take to fix and prevent yellow aquarium gravel.

1. Check water parameters.

It’s essential to know the exact cause that resulted in the discoloration of water. Therefore, begin with checking the level of nitrites, ammonia, nitrates, and pH of your aquarium water.

At the same time, also look for floating debris, decaying plants, and food waste in your aquarium water. These can be the leading causes of water and gravel discoloration.

Additionally, try to look for any decaying fish lying or trapped under decorations or substrate. Rotting fish can also impact the water quality.

2. Install filtration system.

A good quality filter is vital to maintain aquarium hygiene. It traps the floating debris and also eliminates the dissolved toxins from the water.

It’s also essential to clean the filters regularly to avoid waste buildup and clogging. Periodic maintenance and changing cartridges and filter media will ensure that the filters continue to work efficiently.

You can determine the filter size by taking into account the size of the aquarium and the number of occupants.

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3. Cure driftwood.

The driftwood placed inside the aquarium should be cleaned thoroughly with a brush to remove the dirt and debris.

Additionally, you can soak the driftwood in water to leach out the tannins responsible for discoloring the gravel and water. Tannins won’t harm the aquarium occupants, but they can lower the pH over time.

Finally, you can boil the driftwood to sterilize and eliminate the unwanted pathogens that alter the water quality.

4. Regularly clean the substrate.

The substrate can clean the organic waste, decaying plant matter, and food waste. However, over time they can make the substrate dirty.

So regularly cleaning of the substrate can ensure that the trapped debris and waste don’t rot and release toxins like ammonia and nitrites into the tank water.

Furthermore, by regularly cleaning the substrate, you can eliminate unwanted waste and pollutants. This will enhance the aesthetics of your aquarium and help maintain a healthy environment for your aquatic inhabitants.

5. Regularly change the water.

Regular water changes can avoid the buildup of algae and harmful bacteria on the aquarium gravel. They will also ensure that the waste is disposed of and proper hygiene is maintained.

Besides maintaining hygiene, clear water gives an aesthetic appeal to the aquarium by enhancing the display of decorations, aquatic pets, and live plants.

6. Remove decaying plants.

It’s essential to remove the decaying plants and stray leaves from the aquarium. These items can harbor various microorganisms, which can lead to outbreaks of diseases in the aquarium occupants.

By removing decaying plants, you can maintain hygienic conditions, avoid discoloring of the gravel, and enhance the overall appearance of the aquarium.

7. Control food waste.

Most hobbyists make the common mistake of overfeeding their aquatic pets. However, it harms them more as the excess food tends to rot.

Moreover, it impacts the aquarium’s hygiene and depletes the water quality. Excess feeding also makes the water yellow and dirty. It increases ammonia buildup and depletes oxygen levels too.

Therefore, it’s essential to feed the fish with the correct quantity of food to avoid wastage and maintain hygiene and water quality.

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8. Avoid overstocking.

Overstocking means that there are too many fish inside the aquarium. An overstocked aquarium will undoubtedly put pressure on the aquarium filters and other aquarium equipment.

It will result in excess fish waste that affects the substrate, making the gravel and aquarium water dirty. Therefore, it’s best to have the correct number of fish to ensure a healthy and clean aquarium.

The above preventive measures can help you maintain the required hygiene and balance in your aquarium.

However, regular maintenance and periodic change of aquarium equipment will ensure that your gravel continues to eliminate the waste and toxins from the water.

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