How Much Gravel Is Good For My Aquarium?

The aquarium gravel is the most well-known substrate that may come with various colors to make the aquarium more attractive and charming. When you collect gravels to use it in your aquarium, you may find a polymer seal upon the gravel that ensures you it doesn’t create any harmful effect on the water.

 What if the gravel is too much in your aquarium than its needs or the gravel is significantly less than its required?

Too much gravel in the aquarium can make your daily maintenance harder as like as less amount of gravel. On the other hand, adequate gravel let beneficial bacteria grow and live well. So, you should keep a sufficient amount of gravel in your fish tank.That’s why It’s very important to know how much gravel needs an aquarium. And, in the post, I have discussed in-depth below.

Aquarium substrate means the type of material that is kept at the bottom of the fish tank and is able to make a natural environment for fish. It can also impact on aquarium water and build an attractive look. The aquarium substrate could be gravel, soil, marble, sand, dirt, etc.

Before keeping the substrate in your aquarium, you have to be always concerned about its shape.

A substrate that is sharp in shape can be harmful to your fish. Especially if you have bottom-dwelling fish, you should never put this type of sharp substrate. It can damage the physical health of your fish.

Differences Between Gravel and Substrate

The substrate is the things that refer to the gravel, sand, or something like that you can use at the bottom of your aquarium. On the other hand, gravels are a kind of substrate. That means both are almost the same when it comes to putting into the aquarium. You can keep anything as a substrate in your aquarium as well as gravels if it works for you. 


Here keep in mind that gravel is not only a substrate. It’s just a part of the substrate and can be included with other types of material.


There are various types of gravel available for use to aquariums and each of them size may have 3-5 mm, wherein the natural gravel is 3-25 mm. Any gravel that is smaller than 3-5 mm can cause of growing anaerobic bacteria. Because when you are using sand and smaller gravel together, there is prevented oxygen and normal water flow.


In the gravel, there is usually no nutrient component. On the other hand, substrates are combined in such a way so that it contains minerals and nutrients. These are beneficial to aquarium plants, fish, and the overall environment. This is the main difference between substrate and gravel. The substrate can also come with various colors and maintain PH, GH, and KH.


Sometimes gravels need to be washed before using a planted aquarium. But, substrates are prepared for instant use.

How Much Gravel For Aquariums?

I have mentioned above that gravel is a kind of substrate, and the substrate is the most important part of your aquarium. When you think about gravel as a substrate that you want to put at the bottom of your aquarium, the first question you may have in mind how much gravel need for your planted aquarium.

The answer to your question is depends on several factors that are essential to keeping the right amount of gravel. If some factors are overlooked, you may feel difficult to maintain your aquarium. It plays a vital role in an aquarium. Keeping the right amount of gravel can make your fish tank more decorative and attractive.

The factors you should consider before evaluating the amount of gravel;

  • Aquarium Size: The size of your aquarium should be the most important priority when measuring the gravel quantity you want to put on. The volume of gravel mostly depends on the size of your aquarium.
  • Plants And Fish: What types of plants and fish you have in the fish tank can affect on your measuring. If you have a large size of plants that need much gravel to anchor their root, you have to put the gravel base on their needs. On the other hand, if you have such fishes that are not suitable for your desired amount of gravel, considering the re-measuring is the best way.
  • Space and Beneficial Bacteria: Before going to keeping gravel in your aquarium, consider the tank’s inside space and beneficial bacteria. Keep the gravel in such amount so that it can provide adequate space and help to grow useful bacteria. Sometimes helpful bacteria can be destroyed for keeping the imbalanced substrate.

 It is considered that 2 inches of gravel as a substrate is averagely good for a freshwater aquarium. Though it is thought of as a minimum to many aquarists, it is average. However, determining the exact amount of gravel as a substrate, you have to calculate your aquarium dimension and size.

This is typically said that 1 to 2 Ibs gravel for each gallon water is ideal. That means, If you have a 10-gallon fish tank, you can keep an average ±15 Ibs gravel in your fish tank. If you are still confused, use a gravel calculator for measuring more accurately.

Use this gravel calculator (Calculator) by putting the right size of your aquarium length and width. It calculates for you automatically how much gravel you have to keep in your aquarium. It provides you the gravel depth by Inches, centimeter, foot, and meter. 

How Much Gravel For 3 Gallon Fish Tank?

For each gallon aquarium, 1 pound of gravel is considered ideal. If you have a 3-gallon aquarium tank, then you have to put an average ± 3 pounds of gravel substrate.

How Much Gravel For 5 Gallon Aquarium Tank?

For a 5-gallon aquarium tank, you can put five pounds of gravel. But keeping a little more gravel wouldn’t a problem if other requirements are being adequate.

How Much Gravel For 10 Gallon Aquarium?

If you have a 10-gallon aquarium, you can keep ±10 pounds of gravel as it is thought an average amount. Keeping some more or less wouldn’t be a major problem for aquarium.

How Much Gravel For 20 Gallon Aquarium?

In a 20-gallon aquarium, you can keep 20 ponds or Ibs gravel for your fish tank. For measuring more accurately how much you need gravel to your aquarium, you can use a gravel calculator. Just put your aquarium dimension, and the tools will calculate the amount.

How Much Gravel For 29-Gallon fish tank?

As a substrate, you can put 29 to 38 Ibs gravel for the aquarium. It is considered that 1 gallon of the fish tank needs 1 to 2 gallons of gravel.

How Many Gravel For 40 Gallon Aquarium?

For a 40-gallon aquarium, keeping the gravel between 40 to 80 Ibs is better. Between 40 to 80 Ibs, think about what amount will be looks perfect for your fish tank.

How Much Gravel For 36, 60, 75, 125, Gallon Aquarium?

Think 1 to 2 Ibs (pound) of gravel need for each gallon fish tank. And then calculate based on your aquarium per gallon. If you have a 36-gallon aquarium, you need an average of 36 pounds of gravel. In the same way, calculate for 60 gallons, 75 gallons, 125gallon, or whichever you have.

Do Aquariums Need Gravel?

A Fish-tank doesn’t need gravel essentially, but it can provide to your fish a natural environment. Without gravel, fish can live and thrive in an aquarium as well. But keeping some gravel in the aquarium is a good idea that allows a natural habitat for your fish and plants. 

In an aquarium, substrates can manage fish waste and other debris. Gravel does this same way. In our life, every creature’s need a sufficient amount of microorganisms that can help in waste management. Gravel works in the same way in the aquarium.

Though this beneficial bacteria can grow in an aquarium without a gravel substrate, it is very low to maintain the aquarium environment properly.

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