An aquarium substrate is not just decorative: it affects water chemistry, provides support for plants, and forms part of the habitat for fish and invertebrates. Choosing the right gravel or bottom rock is one of the first steps when setting up an aquarium, whether it's a freshwater tank or an aquascaping project.
What to consider before choosing a substrate
- Mineral composition: some rocks (such as limestone) release carbonates and raise the water's hardness and pH, which is desirable in African cichlid tanks but problematic in planted tanks or for fish that need soft water.
- Grain size: fine grain sizes favour plant rooting; coarser grains make cleaning easier and are common in unplanted tanks.
- Rounded edges: especially important in tanks with bottom-dwelling fish, to avoid injuries.
Common materials
Among the most widely used are quartz gravel, silica sand and various ornamental rocks selected for their shape and colour. Before adding any material to the tank, it should be rinsed thoroughly to remove dust, and if the rocks are of unknown origin, checked to make sure they don't contain components that could alter the water chemistry.
Discover our selection of substrates and rocks for aquascaping, chosen for their controlled mineral origin.