How Much Gravel do You Need in a Fish Tank?

If you are getting yourself ready to set up a fish tank you are certainly excited with all the preparation tasks you have to do around it.

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From choosing the ideal tank size and shape to set it up properly, there are many things to get right from the very beginning in order to save yourself troubles at a later point.

One of the first things you should do when starting a new aquarium is to choose a good substrate. Gravel is a popular choice used by many aquarists. But how much gravel do you need for your fish tank?

From this article, you can learn how to calculate the amount of gravel you need and how thick the gravel substrate should be.

How Much Gravel to Put in Your Fish Tank?

As a general rule of thumb, I recommend adding 1-2 inches (2.5-5 cm) of gravel to your fish tank. This means, that you will have to get about 1-2 pounds of gravel per gallon of water volume. So a 40 pound (18 kg) bag of gravel should be enough for a 20-40 gallon tank.

Calculate the Weight of Gravel in Your Tank

To put this as easy as it gets, here is how to properly calculate the weight of gravel in your tank.

Let us start with the basic predisposition that 1 cubic inch of gravel weighs 0,05 pounds. Next, let us presume that you have purchased a standard 10-gallon tank. Such tank usually has the following dimensions:

  • Length: 20 inches
  • Height: 8 inches
  • Width: 12 inches.

Now, if you simply add 2 inches of gravel to a fish tank, calculating its weight should become quite an easy task. Here is how to do that:

2 (inches of gravel) x 20 (inches of tank length) x 12 (inches of tank width) = 480 cubic inches x 0.05 = 24 pounds of gravel.

Benefits of Gravel in Aquariums

There are many benefits of using gravel in your fish tank. Here are a few to consider:

– Home for Beneficial Bacteria

Gravel is not just a pretty addition to a tank. Moreover, it provides many advantages both to the keepers who need to maintain the tank as well as to the fish which live in it. And its most important and ultimate advantage is providing a home to beneficial bacteria. These are essential for any functioning ecosystem, including a captively kept one.  

Colonies of beneficial bacteria will easily find a suitable home among the gravel, which is highly necessary. Indeed, this is what ensures at best that fish waste, as well as decaying plant matter and food leftovers, are being properly dissolved. As a consequence, there should be no ammonia spikes in the water, which ultimately brings to a healthy living environment for your beloved fish.

– Collects Debris

Secondly, a substrate made out of gravel can help greatly into having a visually cleaner tank. Imagine if your tank had no substrate at all. Where would all that debris go before being decomposed by bacteria? Well, either onto the glass bottom or floating along the water. Either way, not a pretty sight.

When having gravel at the bottom, small particles of debris will manage to stay caught in it, having no opportunity of floating around the water unless someone disrupts the gravel. This is actually an excellent method in maintaining your tank not just healthy, but also visibly clean and clear. 

– Grow Live Plants

Aquatic plants can be grown in gravel, and they grow really well. So you should consider adding live plants to your fish tank.

Everything is so much better when there are live plants around, including aquariums. Apart from making your tiny eco-system look more natural and healthier, plants bring to so many beneficial factors.

They improve oxygenation levels among the tank water, which is obviously highly appreciated by any fish which lives in it. Additionally, they offer protection from direct sunlight as well as a safe refuge for smaller fish that need to hide in order to survive (or thrive).

Plants compete with unwanted algae for nutrients, meaning that you will have less necessity in scratching ugly algae away from various surfaces.

With gravel, you are basically offering your plants the basic predispositions for an ideal growing environment. You can either add some nutritive additions to your gravel so that plants get the maximum out of it, or gravel can simply be used as a solid base for proper rooting activities.

– Easy to Maintain

Gravel is a quite simple yet thankful substrate type for maintenance. Indeed, it is too heavy to get caught in the filter if we compare it for instance with a sandy option. Furthermore, it is so easy to clean by performing more or less regular vacuuming.

Such cleaning methods will ensure that all debris is carefully removed from the tank, without the danger of gravel particles getting caught inside the vacuum.

– Looks Natural

Last but not least, gravel looks pretty amazing in any tank, and it certainly adds a natural feel to the entire area. Your fish will love it. And some of them, depending on the species, may even decide to dig into it occasionally and enjoy its presence. What else is there to add?

Do You Change Aquarium Gravel?

Generally speaking, there is no urge of replacing the aquarium gravel at all. Instead, with regular and carefully performed vacuuming activities, it may spend several years there with no need of being changed.

This can ultimately ensure that your fish have a nice and steady routine without having to disrupt it with occasional re-decorations. And of course, you will have fewer things to think about.  

Wrapping Up

Not all fish species can live in a tank set up with a gravel substrate. Some of them will require strictly sandy substrate. Others, more rarely, will not manage to adapt to anything more than a bare-glass bottom.

However, most of the aquarium fish species can thrive perfectly fine with some helpful gravel on their home’s bottom. And if your fish are among the last ones, we highly suggest picking gravel every time.

Substrates made of gravel can greatly help with maintaining a healthy colony of beneficial bacteria, collecting visible debris, and growing amazing plants. And, on top of that, it looks great natural and requires low maintenance.

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