Substrate: Get aquarium sand or gravel?

aquarium sand

When it come to the aquarium floor, you have to make a choice of the substrate

The Aquarim sand or substrate takes on many important tasks in the aquarium. It filters the water, provides nutrients and support for plants and, through bacteria, is involved in the breakdown of animal and plant remains. Basically, the aquarium floor can be divided into sand and gravel. Since quartz is the main component of sand and gravel, these are also known as quartz sand and quartz gravel.

I will give you helpful information about whether you should buy aquarium gravel or rather use sand.

On this guide you will find information on:

What is the difference between aquarium sand and gravel?

Very simple: Up to a grain size of 2 mm one speaks of sand. Anything larger than 2 mm in grain size is called gravel. You can buy normal aquarium sand with a grain size of 0.5 – 2 mm. Fine aquarium sand is often bought with a grain size of 0.1-0.5 mm or even finer. More details about sand can be found on Wikipedia .

But be careful, there is often talk of fine aquarium gravel, which actually means sand. Here you should be careful that there are no misunderstandings. Therefore, when buying aquarium sand, always pay attention to the correct grain size.

What is The Best Aquarium Sand?

Which aquarium gravel or sand should I buy for which fish species?

Which aquarium substrate you choose depends crucially on which fish species you want to keep. In general: play box sand is often treated with fungicides and must not be used in your aquarium! Construction sand from the hardware store is also not suitable, as it has a very irregular grain, is sharp-edged and extremely dusty.

Aquarium substrate according to fish species:

Gobbling & digging aquarium fish

Ground dwellers like the armored catfish (lat. Corydoras) prefer fine aquarium sand, as they can easily dig through it and it enables the bottom fish to “flush” their gills.

Sand is the ideal aquarium floor for burying fish (thorn eyes or fin suckers) and for many snail species.

Many species of cichlids (Latin: cichlids) dig or chew the aquarium sand for food residues and create spawning pits in the aquarium sand.

Best tip: Buy fine aquarium sand for goby or burrowing fish

Invertebrates – Shrimp and Crayfish

For dwarf shrimp or crayfish, coarser sand (0.5 mm – 2 mm grain size) is suitable, as they also search the aquarium floor for food but lift the grains and turn them with their claws. This grain size can also be used for many community aquariums.

On Amazon you will find a large selection of aquarium sand (shrimp gravel) especially for shrimp and crabs.

Other aquarium fish

For many fish it makes no difference whether they are kept on an aquarium gravel or sand. There are enough ground dwellers (aerial catfish, loaches, etc.) that can be kept on gravel without any problems. Some cichlids prefer coarse gravel as this resembles their natural habitat. Aquarium plants can be fixed better with aquarium gravel. The plant will then not come out of the substrate so easily.

How much substrate should I buy?

The amount of substrate should not be saved. The motto here is: a lot helps a lot. Because only with a sufficient height can the roots of the plants develop well. Roots or stones can be anchored much better in a high aquarium substrate.

For most aquariums, between 5 and 10 cm in height is recommended, depending on the size of the aquarium tank. If you intend to buy a nano aquarium, 5 cm of aquarium gravel is sufficient. For larger aquariums with correspondingly larger plants, it should be 10 cm or more.

How to calculate how many kg of aquarium gravel or sand you should buy:

Floor height X aquarium length X aquarium depth / 1000 = gravel volume in L

Gravel volume in L X 1.5 kg / L = aquarium gravel  in kg

Example calculation for a 100 cm aquarium with a floor height of 10 cm:

10 cm X 100 cm X 40 cm / 1000 = 40 L

40 LX 1.5 kg / L = 60 kg aquarium gravel

If you want to buy fine aquarium sand instead of gravel, increase the value from 1.5 kg / L to 1.6 kg / L. For a 100 cm aquarium you then need 64 kg of aquarium sand.

Create a sand island

If you have already set up an aquarium with gravel and you find that your bottom dwellers prefer sand, then you can build them a sand island. To do this, you put a suitable vessel (bowl, bowl, etc.) in the aquarium gravel and fill it with the sand. Alternatively, you can separate part of the aquarium bottom with a plexiglass and fill in the sand there.

‘The Island’ aquascape step by step

Lime-free and not sharp-edged sand or gravel

It is always important to use lime-free aquarium gravel or sand so that the hardness of the water is not affected. Play box sand or construction sand from the hardware store is sharp-edged and not suitable for an aquarium! Aquarium fish, especially goby species, can injure their mouth and barbels on sharp-edged substrates. Above you will find the ideal aquarium gravel or sand for your pool.

What color should the sand or gravel aquarium be?

Gravel and sand come in a wide variety of colors and grains. Depending on your preference, a dark aquarium gravel or sand is more suitable, as this allows the colors of the plants and fish to come into their own. A dark back wall further increases this effect. The bright colors of the shrimp look particularly intense on black aquarium sand .

For Amazon basins, you should buy aquarium sand or aquarium gravel, which is available in darker red, brown to black tones. On the other hand, lighter gray to white tones are suitable for African aquariums in which African cichlids are preferred.

The fish don’t care if the bottom is blue, green or red. In the end it all depends on the eye of the beholder, because: What pleases is beautiful.

aquarium sand
Aquarium sand

What should you do if the aquarium sand rots?

For many fish, sand is the most natural substrate and comes closest to their original biotope. It also has the advantage that the sludge remains on the aquarium sand and can be vacuumed more easily. With aquarium gravel, the sludge gets into the gaps faster and sinks deeper and deeper into the aquarium floor.

Then what is the cause of rotting and darkly discolored aquarium sand? On the one hand, roots of aquatic plants can die off and begin to rot in the soil. In addition, a sore spot can arise when sinking forage is worked into the sand by bottom dwellers.

Vacuum the rotten areas including the sand completely. If you have a lot of rotten spots, I recommend changing the sand completely. The rotten areas pollute the aquarium water and harm the fish and animals. You can find the right aquarium sand above in the article.

Preventive measures:

  • Clean the sand surface regularly.
  • Feed in different places in the aquarium.
  • Loosen up the aquarium sand after cleaning the surface.
  • Used tower screw conveyor (TDS). They are the earthworms of the aquarium.