When it comes to the care of aquarium plants, there is one question we are asked more often than you would think. The topic of the substrate and how much to add to your aquarium is one of much confusion. However, this can be explained in a way that makes it very easy for anyone to calculate the right amount of soil that is both effective and looks great.

It is important to understand that unlike in nature, a deep substrate in the aquarium can cause problems. Deep substrates can trap decomposing plant matter. That being said, a substrate to thin and it won't be able to support healthy plant growth either so what is the right amount?

Some plant species like Amazon Sword or Crinum calamistratum grow large root networks and draw most of their nutrients from the soil and as such, a substrate which is between 3 and 5cm will be enough space for healthy growth.

On the other hand, stem plants such as Ambulia have much thinner roots and receive most of their nutrients from the water so ideally, a substrate depth of around 2.5cm to 3cm is really enough.

You can calculate the right amount of aquarium soil for your next substrate by using this formula based on the depth you want and the size of your aquarium.

Length (cm) x width x chosen depth of substrate. You can then take this number and divide it by 1000 to give you the number of litres of soil to add to your aquairum.

An example of this would be the following:

You have an aquarium that is 60cm long and 30cm wide and you wish to grow amazon swords along with various stem plants. The best depth would be between 4-5cm to provide the best climate for the larger root network of the Amazon sword plants. Your calculations would be as follows.

Length (60cm) x width (30cm) and 5cm (substrate depth) = 9000 / 1000 = 9l of soil required.

This is the best way to work out the ideal volume of aquarium soil to effectively grow aquatic plants. We hope that this is helpful to you when it comes to planning your next aquascape.

Check out our range of aquarium soils here