How Much Gravel For Fish Tank? (This Right Amount!)

If you’re setting up a new fish tank, congrats! You’re about to start a fun new adventure in the world of aquatic animals.

However, setting up a tank requires you to have some pretty important prior knowledge when it comes to water, fish, and accessories. One thing you need to know about is a substrate for your fish tank, such as gravel.

If you plan to use gravel for your fish tank, you want to make sure you put the right amount. Typically, you should use one pound of gravel per gallon of water in your tank.

This means if you have a 10-gallon tank, you’ll need about 10 pounds of gravel. Easy, right?

However, not all gravel is the same. Below, we’ll talk about:

  • The different types of gravel, 
  • How much of each type of gravel you need to use, 
  • And how to clean your gravel.

To learn more about using gravel in your tank, read on!

What’s The Purpose of Using Gravel in Your Fish Tank?

You may be wondering why gravel is even important anyways. Isn’t it just to make the tank look pretty?

Not always! Like other substrates, gravel can actually be a useful tool in your fish tank. Some reasons you may use gravel include:

  • You have bottom feeders or your fish don’t burrow much
  • You want something easier to manage than sand
  • You want to prevent bacteria from building up in your substrate

Typically, gravel is best for tanks with bottom feeders that can eat algae and other debris off the tiny rocks. It is also best for fish that cannot swallow sand and won’t burrow themselves all the time. 

If you have a fish that likes to burrow and sharp gravel, your fish could hurt their soft belly. Always make sure the aquatic species you’re getting are the best to use gravel with!

Plus, gravel is often easier to manage than sand because it is easier to clean and prepare. Since there’s space for water to flow between the rocks, bacteria and amoebas will have a harder time building up than in other substrates. 

What Are Different Types of Gravel in Fish Tank?

Though you may simply be used to seeing the standard, colorful aquarium gravel at your local pet store, there are actually many different types of gravel out there. These types include:

  • River rocks
  • Mini pea gravel
  • Inert gravel
  • Active gravel

Please note that there are actually even more types of gravel than these! These are just the most common types available at your local shops. 

1. River Rocks

Though not seen as often as other gravel types, river rocks make a great choice for substrate in your tank. River rock gravel is made of larger stones than other types of gravel, which is an attractive choice for your tank.

River rocks often reduce the chance of bacterial buildup as there is more space between the rocks for water to flow than with smaller gravel. Plus, river rocks allow bigger areas of space for bottom feeders to eat off of. 

Finally, river rocks are a great choice if you’re worried about your fish accidentally swallowing gravel. In particular, river rocks are great for goldfish owners that are concerned about this, as goldfish are known to put objects in their mouths that they’re later unable to remove. 

2. Mini Pea Gravel

Mini pea gravel is the most common gravel available at your local pet store. Whenever you see gravel that is brightly colored to decorate your tank, this is often a type of mini pea gravel.

Mini pea gravel consists of extremely small pieces of rock, which produces a finer finish in your tank. Though there is a greater risk of swallowing, it is a better choice for fish that occasionally burrow, as it is easier for the pieces to move gently around your fish.

If you’re looking for gravel with lots of options, the mini pea is the way to go.

3. Inert Gravel

Inert gravel is simply gravel that does not have added nutrients to it. Nutrients in your substrate can help change the water chemistry in your tank or can help provide your aquatic plants with necessary food. 

The normal gravel you get at the store that is colored rocks is inert gravel. If you don’t want your gravel to affect your plants or water chemistry, it’s best to stick to this.

4. Active Gravel

Active gravel, as implied above, is a gravel that contains nutrients to change your water chemistry and feed your plants. Though not as popular as inert, it can be incredibly helpful to those with plant-heavy habitats.

Active gravel is more than just rocks. Often, this gravel consists of stones or hard clay and can also contain some soil in the mix to introduce natural bacteria to your tank. 

It may be a bit more expensive than inert, but can be worth it as it often saves you later in liquid fertilizers. 

Fish Tank Gravel Calculator: How Much Gravel Do I Need?

As mentioned at the beginning of this article, the rule of thumb is to add a pound of gravel per gallon of water to your aquarium. So, if your tank is 20 gallons, you should aim for around 20 pounds of gravel in your tank.

However, this value may vary slightly depending on the type of gravel you have. For example, river rocks will have fewer rocks per pound since the rocks themselves are larger. 

In this situation, you may want to consider adding more river rocks to make up for empty space if you feel the layer of gravel is not thick enough.

You may also want to add less active gravel, depending on how many nutrients you wish to add to your tank. A combination of inert and active gravel may be helpful for those wanting to add fewer nutrients to their tank.

On average, your gravel layer should be approximately two inches deep. This is deep enough to anchor plants and provide a solid base without taking up too much swimming space for your fish. 

If you put too much gravel, it will be easier for dirt and bacteria to accumulate on the bottom. Too little, and you won’t be able to anchor plants or other accessories. 

If you follow the pound and inches rules, you should have just the right amount of gravel in your tank!

What’s The Best Way to Clean Aquarium Gravel?

Like all other substrates, gravel doesn’t stay clean forever, just like any other animal, fish poop – a lot. 

Gross, we know. But it’s true!

Eventually, the time will come when you need to clean your gravel to keep your fish’s tank clean and healthy. To do this, you have a few options:

  • Gravel siphon
  • Turkey baster
  • Bottom feeders

Between these options, your tank will be clean in no time.

1. Gravel Siphon

The easiest way to clean the gravel in your tank is using a gravel siphon. A gravel siphon is like a small vacuum that can be used to suck out the water and, well, gravel!

Always make sure your fish and other species are out of the way before using your siphon. You don’t want to accidentally suck them up too!

After siphoning the gravel out of your tank, you can then clean it how you see fit. This can include rinsing, boiling, or other cleaning methods. 

Just make sure not to use harsh chemicals, as these can stick to the gravel and get into your tank later if you reuse it. 

If you plan to just put in new gravel, try to repurpose your old gravel, such as putting it in your driveway or using it to help repot plants!

Use, reuse, recycle, as they say!

2. Turkey Baster

If you don’t have a gravel siphon, have no fear! Your favorite Thanksgiving tool is here to save the day. 

A turkey baster is a simple solution to your gravel problem. Use your turkey baster the same way you would when cooking and suck out the dirty gravel. 

The turkey baster can also be great for spot cleaning when you don’t plan on fully changing out your gravel just yet. 

Once the gravel is removed, clean or replace as described above. 

3. Bottom Feeders

To reduce how often you need to clean out your gravel, you could add some bottom feeders to your tank! Some examples of common bottom feeders include:

These organisms will eat any dirt and debris off the top layer of your gravel, which improves the cleanliness of your tank and decreases how often you have to clean it yourself. Talk about economics!

Now You Know

Now you know how much gravel to include in your fish tank! Remember, you should aim for a pound of gravel per gallon of water, but you may have to adjust depending on your gravel type.

You also need to consider the type of fish you have. If you have a fish that burrows or needs sand to help them digest, gravel may not be the best choice for you. 

If you prefer gravel for your tank, tell us which gravel you use below and why it works best for you. If you have any questions about your home aquarium, ask us below, and we may answer your question next!

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