Best Substrate For Aquarium

What is the aquarium substrate and how important is it?

Choosing the substrate for the aquarium or the absence of any type of substrate, is one of the first decisions we will have to make when setting up our aquarium.

If you are starting in the aquarium you will be wondering and with good reason, what difference, the advantage or disadvantage that different types of substrates have, or ifyou can go from putting substrate in the aquarium… Total, then you have to clean the aquarium and the substrate is a nest of bacteria and dirt.
Ummmm… good and bad.

I will answer you the first time.
The substrate is that sand, gravel or organic material that is placed in the bottom of the aquarium.
It has different functions. One and the most important is to promote the development of bacteria, which will help the nitrogen cycle to complete .

Although it may seem to you that it is a source of dirt, it actually fulfills a very important function to maintain the aquarium’s ecosystem , and if we also have plants, it will serve to support their roots.

The plants aquarium are very importantand we must weigh a lot whether to place them or not.

I personally recommend its use, obviously your choice has a lot to do with the type of aquarium, the species of fish that we are going to take care of, etc. But they are essential to maintain the health of the aquarium … just like the substrate.

Best selling aquarium substrates

What substrate are you looking for?

With so many types of substrate, which one do I choose?

Before making the final decision, I recommend you read the article completely, surely you will have much clearer what type of substrate is the best for your aquarium.

In the market you will find a significant amount of substrates, although they can basically be divided into three large groups, the inert, the nutritive and the clay.

Inert substrates

Inert substrates are basically made up of gravel and sand , with an almost infinite number of options in terms of size and color.

It is important that when you are making the purchase decision, you discard those artificially colored sands or gravels, as they usually have chemical components that can be toxic to fish.

Advantages and disadvantages of inert aquarium substrates

Like any choice you make to set up your aquarium, you are going to find positive and negative aspects.
As advantages I would highlight:

  • They do not influence the quality of the water
  • As they do not modify the quality of the water, they allow us greater control over the aquarium parameters

Of its advantages, its main disadvantage appears :

  • We cannot place aquarium plants that need a substrate to survive or to hold on. They have to feed through the leaves

Types of inert substrates sand and gravel

Well, maybe if you are starting with your aquarium, you have already made the decision to use an inert substrate, which seems to be the most suitable for beginners, but… which one to choose? The variety is wide.
I’m going to show you the different options you can choose from, with their main characteristics:

Aquarium sand

Aquarium sands are 0.5 to 2 mm thick. This thickness is called granulometry, and you will find coarser and finer sands.
Before deciding on sand, you have to know the advantages and disadvantages of this substrate.

  • Sand can cause problems in the long run because it tends to compact , interrupting the water and air cycle, creating anaerobic conditions. I invite you to read about the nitrogen cycle , you will understand that they are the least desired conditions for the good health of the aquarium.
  • In the sands everything is not going to be bad, they are very decorative. In combination with other elements, such as plants, gravel, rock or logs, it creates a great feeling of naturalness and originality.
  • We can choose to use them as a complement and place them in certain areas of the aquarium where there will be no plants, or also as a final cover, on a main substrate.

What differentiates gravel from sand is size. We speak of gravel when the size of the granules is between 2mm and 5mm.

Thanks to their size, they allow water and air to flow through them , facilitating oxygen exchange and preventing harmful toxins from appearing for the aquarium’s ecosystem.

As an inert material, they do not influence the parameters of the aquarium, although they fulfill their primary function, favoring the appearance of beneficial bacteria.

They can be used alone or in combination with other substrates, being equally decorative, such as sand.

Clay substrates

Despite the fact that clays could (or should) be classified as an inert substrate, the truth is that if they have the ability to change the parameters of water, that is why they deserve a separate chapter.

Clays contain nutrients such as iron, aluminum oxide or magnesium, and they release them into the aquarium over a long period of time.

They also have another very curious quality.

They have the ability to exchange ions . They are loaded with negative particles, which attract the positive ones, such as calcium or magnesium, which makes it easier for them to be absorbed by the roots of the plants.
It is not usual that they are used as the only substrate, rather as a complement to a nutritive substrate, at the bottom of the aquarium and mixed or under an inert substrate.

It should not be used as a covering substrate, as they contain dust particles, which leave the water cloudy for a long time, until they are able to settle.

I think it is interesting to list  the advantages and disadvantages that you will find when using clay as a substrate:

Advantages and disadvantages of clay substrates


  • They help to adify the water, reducing its pH and therefore its hardness.
  • Thanks to the fact that they have negative charges, they help retain nutrients and are absorbed by plants.
  • They improve the circulation and oxygenation of the water.
  • They help hold the roots of aquarium plants in place.
  • They facilitate the appearance of bacteria, helping to improve the health of the aquarium through biological filtration.


  • By moving the clay substrate in the aquarium, we will create a little chaos. The water turns cloudy and brown in color.
  • Its presence influences the quality of the water and its parameters. Sometimes it is difficult to stabilize them.

In short, they are a very interesting option to consider, halfway between inert and nutritious substrates, but which must be treated with caution and perhaps they are not the most advisable substrates for newbies.
You can find three types of clays for sale:


Akadama clay comes from Japan and is of volcanic origin. Some varieties are used in the cultivation of Bonsai.

For the aquarium we will find different Akadama clays, classified according to their thickness (granulometry), their homogeneity and consistency.


It is a clay also of origin in Japan. It is mined from the mountain in the vicinity of the city of Kiryu and is also of volcanic origin.

The great advantage that this clay has is its ability to stabilize the pH of the water in intervals of 6.5 to 7.


It also comes from Japan (city of Kanuma) and is of volcanic origin, it is lighter than the Akadama and has a much lighter coloration.

It has a more acidic pH, around 6.

Nutritive substrates for planted aquariums

Nutritive substrates for aquariums, if they have the ability to modify water parameters such as pH, gH and kH, because they contain a large amount of organic matter, which serve to provide nutrients to the aquarium plants.

All the nutritious substrates for aquarium that are sold, usually contain organic matter and also a part of clay.
When using this type of substrates, the ideal is to put a layer of gravel on top. If we choose not to use this option, it is advisable to put a more porous substrate (clay) under the substrate, which helps to fix the roots of the plants.

Before deciding on any of the different types of nutritive substrates, I advise you to askhow they can influence the water parameters. Keep in mind that water is the most important thing in the aquarium, its quality will influence the plants themselves and also the fish and other living elements in the aquarium.

Types of nutritive substrates

Although all nutritive substrates have the same function, they can vary depending on their structure, as well as their composition.

Enriched nutrient substrates and unique substrates

They are specifically designed for planted aquariums and are composed of laterite to which organic and mineral matter is added, which release nutrients over very long periods of time.

On the market we can find different types of enriched nutritive substrates, with different granulometry, designed to be used alone (only one layer), or to be combined with inert substrates, gravel or sand.

Those that are intended to be used alone, are very aesthetic, have very pleasant black or brown colorations.
Within the enriched substrates, we can find some specific ones to preserve the aquarium parameters at certain levels, which are suitable for the aquarium plants.

These substrates force us to plan very well what our aquarium is going to be like before starting, since from the beginning we have to place a good number of plants, to keep the water in optimal parameters.

** A well planted aquarium needs a lot of cycling maintenance during the first months. The aquarium water should be changed by 50% every two or three days, so that the parameters are not unbalanced.

Soil-type substrate: nutritive substrate and inert substrate

The soil type substrate is the best that can be used, if we want it to contain long-lasting nutrients.
However, it is not the most suitable substrate for those who start in the aquarium, due to its high concentration of iron, carbon and nutrients, which can make life very difficult for a novice.

Soil-type substrates must be used in combination with inert ones, placing a thick layer of soil-type substrate (2.5 to 4 cm), to finish with a layer of fine gravel (inert substrate).

For the more experienced, using the soil type substrate, provides other added advantages, such as that they release CO2 slowly, eliminating the need to add it artificially.

During the first week of use, it releases a large amount of nutrients and organic matter, which can be potentially dangerous for aquarium fish.

For those starting out, it is not very advisable to use these substrates.

Tips for choosing the best substrate

  • For beginners , it is best to opt for a totally inert gravel substrate. The sand should be used for decoration only.
  • Ask what type of aquarium you want to have, what biotope you want to recreate or if you prefer a shrimp.
  • Choose the plants that will be part of your project. Ideally, start with low-maintenance plants to increase the difficulty.
  • Use nutritious substrate, only in those areas of the aquarium where you are going to place plants. Seal the nutrient substrate with inert gravel on top.
  • If you have experience and want something more, you can opt for unique substrates or mixed with decorative sand and gravel.
  • This choice requires having a good number of plants, so it is only recommended for the most experienced.

Calculate the amount of substrate needed

Substrates, gravels and sands are not sold by the kilo, but by the liter.
We must calculate the number of liters of material we need, depending on the height that we want to provide substrate or gravel.
What we calculate is the cubic centimeters and then we convert it to liters.
Measure the length, width, and height you want the sutrato to be.
*** For example, 100 cm long for the aquarium X 50 cm wide X 5 cm high for the substrate = 25,000 cm3 (cubic centimeters), we divide it by a thousand, to know the liters = 25 liters.

Where to buy substrate for aquariums?

The best online stores to buy substrate for aquariums are:

  • Substrate for aquarium Amazon
    In Amazon you will not only find the best brands of substrate for aquariums, you will also find the different formulas that each of them have for sale, with the best prices on the market. If you are looking for a cheap aquarium substrate, this is the best store to find it.
  • Substrate for aquarium Kiwoko
    Kiwoko is a network of pet stores, which has a good selection of aquarium products, among which we find substrates. It doesn’t have as much variety of brands and formulas as Amazon, but it is a good option, at least for comparing prices.

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