How Much Gravel Do I Need for My Aquarium?

How Much Gravel Do I Need For My Aquarium

Gravel is a very important component of any aquarium. However, with gravel store-bought packages being sold in large and varying quantities, it may be difficult to ascertain your needs from your stores’ personal gain benefits. 

As a good rule of thumb, adding one pound of gravel per gallon is usually a solid starting point although that recommendation needs altering depending on a couple of key factors. 

These factors include the aquatic life you choose to support, the plants, decorative purposes and sizing, as well as knowledge about bacterial growth production.

Why Do I Need Gravel?

Gravel is a great middle ground for making your aquarium feel as natural as possible and providing a healthy environment for your wet life in the aquarium. Also known as substrate, it can make a somewhat boring tank look beautiful and stay cleaner for longer.

Other people may choose to use substitutes such as sand, but this sand, depending on what animals and plants you choose to plant in, can easily be disturbed and clog important machinery leading to the demise and deterioration of your mini-ecosystem.

For health, habitat, and aesthetic reasons, gravel is certainly a positive material to be placed into your aquarium.

gravel in aquarium

Finding the right kind of gravel for your wildlife enclosure, since it is not incredibly critical, is largely dependent on your preferences and choices for interior decoration purposes. On the other hand, the amount of gravel you choose does matter.

Whether it be to ensure that the life and animals you include stay healthy, the sizing matches up well, or that the growth in the tank does not interfere with your wildlife, choosing the amount of gravel correctly is extremely critical and important. 

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1. The Wildlife

For a fish only aquarium, substrate, or gravel, is a very practical from an environmental standpoint. In the wild, fish and animals are able to orient themselves by landmarks. The gravel helps orient them to what the bottom of the tank looks like. Usually, glass enclosures are the common trend for aquariums. 

The gravel helps reduce those reflections, decrease anxiety, and increase longevity. Depending on what kind of fish you have, you need different kinds of gravel. For example, goldfish only need about a quarter inch of substrate on the bottom, very similar or close to a bare bottom tank. On the other hand, there are other fish that may need much more.

Perhaps the most important component of the gravel pebbling and covering is how it supports the wildlife that is anchored to the bottom of the enclosure, such as plants. Plants that have weak root systems will not be able to stay upright and balanced if a fish happens to brush against it.

Gravel can help root and secure these plants well. The amount of gravel necessary then depends on the size of the roots. For average midground plants, a good idea is to stack mid-sized gravel approximately 2-3 inches off the aquarium floor with fertilizer sprinkled well and evenly in between. 

This will ensure proper nutrition and a solid foundation to ensure the plants are attached to the gravel and the roots are guided to develop in a mesh-like pattern across the aquarium floor. For example, the Dwarf Hairgrass plant tends to create a carpet-like effect and requires enough gravel to create just a small single layer right over it.

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The larger the plant, the more gravel you will need. Other plants will have different needs of layers. Always check-in and verify what your particular wildlife needs.

aquarium gravel close up

2. The Sizing

The sizing of the gravel pebbling is a significantly important consideration. There are many different qualities to gravel and this will change how much you need depending on the density and compactness of the layers you lay down.

This is part of the reason why gravel recommendations come in inches and weight instead of size (i.e. 2 cubic inches). Otherwise, confusion on the sizing would be rampant. Another size consideration is the actual volume of your tank. 

The rule of thumb does apply, but needs to be well adjusted depending on the type of gravel utilized. There are many kinds of gravel. In general, gravel is a larger sized coating that works well for health and bacterial purposes.

However, there are variations even within this category. There is also variations in textures and quality. Higher quality gravel can be left in the tank for longer, leaving the environment and ecosystem to be undisturbed for longer periods of time. 

This also helps with leaving plants roots strong and healthy. The porous quality of quality, which will in general affect the density of gravel as well is another important note to write down. When measuring pounds of gravel, denser gravel will inherently take up a lesser surface area.  

3. The Bacteria

Bacteria tend to love to accumulate in tanks in general. Especially when you have little fishes, turtles, and plants all over your aquarium, it becomes that much more appealing to the bacteria that love to reside in wet and secluded environments.

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While gravel is most definitely safer in terms of infections and bacterial growth when compared to smaller sized pieces such as fine sand, biological filtration is an important gravel benefit and something to take into account.

 Oftentimes, bacteria can, regardless of the amount of time you refresh the tank, live on the top and within the gravel bed. It is certainly important to keep some gravel though. Keeping a bare bottom tank will cause nitrates and ammonia from fish and animal discharge to accumulate in the water instead. 


Gravel, of course, other than serving a gorgeous purpose, also helps to keep your aquarium clean, healthy, and a flourishing environment for your wildlife enclosure. To ensure that you are giving your animals and plants the best chance they have without sacrificing aesthetic appeals, be sure to be aware of the health risks to various plants and animals, the density and size of both your tank and your gravel.