Here’s A Handy Chart To Find How Much Gravel You Need In A Tank

Gravel is one of the most important components in any aquarium. It provides a surface for the fish to swim on and contributes to the overall filtration of the tank. Knowing how much gravel to use is important because it depends on your tank size and your desired fish load.

No, gravel is not just for aesthetic or decoration purposes. There are a lot of factors that will dictate how much gravel you need, and that is what I will discuss today. But first…

How Much Gravel Do I Need In My Fish Tank? 

Generally, the bottom of your tank should be filled with gravel about 1-3 inches deep. However, the exact quantity of gravel you need depends on what type of gravel you end up using, how much time you are willing to spend on cleaning the gravel, and of course, the needs of your beloved fishes.

Here’s a rough estimate of the amount of gravel you’ll need depending on your tank size:

Tank VolumeGravel Needed

A depth of one to two inches should be adequate for basic purposes. However, bottom feeders need a much deeper substrate than what is usually provided in most aquariums.

Why? The reason for this is because the majority of bottom feeders spend their time digging in the substrate for food, so it would be best to provide them with more substrate to dig around in.

While bottom feeders are generally peaceful, they will still engage in territorial disputes. It is therefore best to give them a lot of gravel bed to discourage disputes.

Now, how do you determine the amount of gravel to add to the tank? You want to have just the perfect amount, not more and not less. Here are two methods you can follow.

Method #1

  1. Multiply the length and width of your tank

For example, if the length is 30 inches and the width is 12 inches, then the product will be 360. 

  1. Divide your answer by 10 

Continuing on the previous example, the answer to this step will be 36

36 lbs is the gravel amount you need to pour into your fish tank of dimension 30×12 inches.

You can further convert this to kilograms by dividing it further by 2.2. So (36 / 2.2) = 15.4 kgs.

These calculations are only rough and meant as a ballpark estimate, so don’t take them too seriously, but they should provide a rough idea.

Method #2

You can also estimate the amount of gravel you need based on the amount of water your tank can hold.

Generally, you require around 1 pound of gravel for every gallon of water. So, for a 15G tank, you need around 15 lbs of gravel.

Again, these are back-of-the-napkin calculations and are meant to give you a rough estimate.

How much gravel do I need in my fish tank?

Why Do I Need Gravel in a Fish Tank? 

A substrate is the bottom-most layer in an aquarium. Gravel is the most common substrate used, but there are definitely other options available. Now, why do you need to add gravel to your fish tank? It’s because it plays an important part in maintaining a healthy tank. In addition, aquarium gravel is safe and doesn’t dissolve or disintegrate into the water.

Gravel has small bits of rocks that are heavy, but not so heavy that it breaks into pieces easily. It is easy to move around on its own and stays together while being moved.

In order to establish the depth of your fish tank, you need to use gravel. You can try anything from small white stones to large pebbles.

Some fish favor fine gravel, while others flourish in coarse gravel. Some fish dig up sand from your aquarium’s bottom so it’s best to use gravel if you are housing them.

Gravel is important for your aquarium because it helps provide bacteria which are beneficial for your tank. Gravel, or any other similar substrate, can encourage bacteria to thrive and grow colonies. If you establish and maintain a balance between your fish and healthy bacteria inside the tank, then your fish will thrive.

Another pro for using gravel is to provide fish some orientation and a sense of direction.

Gravel is also generally easy to maintain. Since it is porous, it prevents any build-up of amoeba and bad bacteria. You can also vacuum gravel to clean it. Being porous makes it easy to extract fish waste and excess food from the bottom.

Things To Consider Before You Opt For Gravel

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1. Do You Intend On Keeping Plants?

You need to look at the plants in your aquarium, some plants without root systems won’t care, but rooted plants draw nutrients from the gravel. 

2. What Does Your Fish Prefer?

Some fish like rough gravel, others like it fine. You need to look at the type of your fish and research if you want coarse or not too coarse gravel.

Frequently Asked Questions

  1. What if I add too much gravel?

    Too much of a gravel might not always be the best. The accumulating debris can sometimes lead to bad bacteria growth. You can’t use a vacuum cleaner with too much gravel on your floor since that leads to dirt and old waste being blown all around the tank, which can cause spikes in ammonia, nitrites and nitrates.

  2. What happens if there is no gravel at all?

    Without a base layer of substrate at the bottom, lights in your tank will reflect off the surface of the water. This will cause your fish extreme stress and can even lead to death. So please add substrate!

  3. What else can I use instead of gravel?

    There are many other substrates you can use instead of gravel. You can use stones, aquarium sand, pebbles, coral or aragonite substrates, and plant-specific substrates, among others. There are different types of gravel that you can use as substrates!

Wrapping Up

I have probably covered everything on the face of this planet related to gravel in fish tanks. I should’ve mentioned that you need to maintain the gravel, because it can get dirty and clog up your filter (it’s not necessary to change substrate often). You can use a substrate vacuum to keep things neat.

Buy only high quality gravel since it will last you a long time. It’s a good idea to add gravel in your tank before any other decorations, water, and fish. Gravel might float and not stay in place if you fill the tank with water first and add it later. 

Ensure that food particles don’t accumulate at the bottom as they stay there; they rot and give out hydrogen sulfide, a very toxic substance. Anyway, I have given you enough warnings for now! Take care of your fish!

Further Reading