How Many Bags of Substrate Is Needed For A Freshwater Aquarium?

When setting up a new aquarium whether freshwater or saltwater the very first that becomes a part of the aquarium is substrate!

Thus, it is essential to know the types, advantages, and most importantly the amount of substrate required. If you are owing to add substrate in your aquarium, you must be sure about the right amount and right type of substrate.

In this guide, we will give you tips that will help you select the right substrate for your aquarium and the accurate amount needed.

What is a substrate?

The substrate is the sand, pebbles, small rocks, or any loose material that covers up the bottom of your aquarium.

Most of the times beginners know what substrate is but don’t know it by name and it gets confusing for them.

So in short anything that covers the base of your aquarium is practically a substrate.

What are the benefits of using a substrate?

Now the question arises of what benefits we can get from using a substrate in a freshwater aquarium.

There are many to name but here are a few of them mentioned.

  • Improves the Aesthetics:

First of all, substrates are the closest thing to the natural fish habitat. Substrate makes the aquarium more realistic and natural for the fish to feel at home.

Moreover, it provides a unique aesthetic to your aquarium, which is the main reason why many people opt to use substrate in the first place.

  • A Storehouse for Bacteria:

The substrate is like a storehouse for beneficial nitrifying bacteria that are major components of the nitrogen cycle. These bacteria are essential for eliminating harmful nitrogenous waste from the aquarium.

So the absence of potential substrate means a lesser quantity of useful bacteria and a buildup of nitrogenous waste.

As discussed above no substrate means a huge buildup of nitrogenous waste and ultimately stress over your fish. Thus, the substrate in a freshwater aquarium is essential for proper growth and disease prevention in fish.

  • Enhances Plant’s Growth:

If you are owing to establish a live planted aquarium, then the substrate is an absolute necessity. Mainly the roots of the plants are the reason behind substrate use. The substrate provides the essential support needed for the roots of the plants otherwise your plants will be floating inside the substrate. 

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What are different types of substrate?

When it comes to choosing the right type of substrate for your aquarium, there are plenty of options available. So, you can select the right type of substrate based on the type of your fish.

The type of substrate used can change your aquarium’s aesthetic completely. Thus, it’s time for you to choose your dream aesthetic.

Following are the commonly used types of the substrate around the globe.

  • Pebbles (most frequently used substrate)
  • Sand
  • Gravel
  • Soil
  • Substrates that can change the quality of water

How many bags of substrates do you need?

After selecting the type of substrate the most confusing point for a fishkeeper is to determine the amount of substrate needed. As in general the amount of substrate for freshwater aquarium is measured on two criteria.

Thickness of Substrate:

The thickness of the substrate in an aquarium depends upon the nature of the aquarium whether planted or non-planted.

1-Non-Planted Aquarium:

As a general rule of thumb, the thickness of the substrate in a non-planted aquarium should be 1-2.5 inches. It is the most acceptable and highly recommended amount by aquarists around the world. Thinner the layer more will be the space available for your fish and decorations and it’s quite easier to clean as well.

The thicker the substrate layer harder it is to clean the substrate thoroughly. Moreover, in a small aquarium of 10–30-gallon, a thicker substrate layer will eventually lead to less space for fish to play around.

The thickness of the substrate is also disturbed in cases of underwater filtration system that increases the thickness of the substrate to another inch.

2-Planted Aquarium:

Live plants in an aquarium are a tremendous combination. Planted aquariums look absolutely stunning and are great in controlling nitrogenous overload.

For live plants to thrive, support and nutrients from substrates are essential. Crucial vitamins and minerals such as magnesium, iron, and nitrates are provided by suitable substrate and water.

In a planted aquarium extra depth of substrate is required to provide grip to the plant roots. Thus, it is highly recommended by most aquarium experts that the substrate thickness should be 3 inches or more in the case of a planted aquarium. 

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The case of plants with long roots such as Frogbit, Cryptocoryne, dwarf water lettuce, and redroot floaters requires a greater thickness of the substrate. A slanting aquarium with thicker substrate around the corners and thinner in the center is another great idea for long rooted plants. A slanted aquarium provides sufficient space for your fish as well.

Plants such as hornwort. Anubias, java ferns, and java moss are excellent choices for the aquarium as they do not require substrate. 

Essential Nutrient Layer:

For those of you planning to set a planted aquarium, a nutrient layer is essential. These nutrients are essential for the growth and coloration of your plants.

A 1-inch thickness of the nutrient layer is usually added underneath the substrate layer. This added layer causes a combined thickness of 3 inches for the plants including the substrate for support and nutrients for growth.  

How many bags of substrate are used?

Understanding the dynamics of accurate numbers of bags required to fill the base of the aquarium to at least 2 inches require lots of calculations and a lot of factors can affect the calculations.

So, to make this easy for beginners in fishkeeping we have made an easy and efficient substrate calculator for you.

Substrate Calculator:

Here is an efficient substrate calculator to calculate the amount of substrate required to perfectly cover your aquarium base according to the aquarium measurements and type of substrate.

All you have to put in the length, width, and thickness of substrate required. The results will surprise you and it is pretty beneficial for beginners to estimate the bags of substrate required.

Factors On Which Amount of Substrate Depends:

The accurate substrate thickness in an aquarium depends upon the following factors.

  • The size and depth of aquarium:

As a rule of thumb, the thickness of the substrate should be 2-3 inches in a 55-gallon tank. Thus, the size, thickness, and width of the aquarium play an important role in determining the amount of substrate required.

  • The inhabitant fish:
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Certain fish types require substrate as it closely resembles their natural habitat. Some bottom-dwellers are habitual of such environment. Thus, for such fishes in the aquarium, it is essential to establish a substrate in the aquarium.

  • The filtration system:

If your aquarium has an established filtration system underneath the substrate, it will change the total thickness of the substrate required.

With the filtration system combined the thickness of substrate should be 3 inches max.

  • Whether the aquarium is planted or not:

A planted aquarium as discussed above requires a greater thickness of substrate for the plants to provide support and nutrients.

  • Types of plants in the aquarium:

Some deep and log rooted plants require more than the normal thickness of substrates such as Frogbit and Cryptocoryne.

Whereas some plants such as Anubis do not require substrate at all.

Frequently Asked Questions (FAQs)

Is substrate necessary for an aquarium?

The substrate is wildly used to improve aquarium aesthetics. They create an environment closest to the fish’s natural habitat. They are a great source of nutrients and minerals for plants.
Despite all this substrate is not an essential component of the aquarium ecosystem. Yes, an aquarium without any substrate is good on its own.

Can aquarium plants grow in just gravel?

Yes, plants in the aquarium can grow without gravel substrate. Most of the plants such as java ferns and mosses do not require substrate at all.
Only deep-rooted plants such as Frogbit requires thick substrate layers with paired nutrient layers for growth.


Thus, the amount of substrate required in a freshwater aquarium solely depends on the size of the aquarium and the type of aquarium planted or not. A total of 2-3 inches of the substrate is usually required.

To correctly estimate how many bags of substrate you needed you can use our substrate calculator.

Remember in the case of planted aquarium an extra nutritional layer is necessary.

I hope we answered all your queries about the quantity of substrate required.

For more queries comment below.

Best of luck with your aquarium!!

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