The material that sits in the bottom of an aquarium is called substrate. There are several different choices for aquarium substrate, the most common of which are sand and gravel. While sand and gravel might seem quite similar, each one has its benefits and drawbacks. Deciding which one to use depends on the types of fish you are going to keep in your tank as well as some other considerations. Our guide will help you decide which is best for your aquarium.
The Case for Gravel Substrate
Gravel substrate is the better choice for most freshwater aquariums. One of the major benefits of gravel is that it allows water to flow through it, preventing the buildup of amoebas and bacteria in the substrate. If allowed to build up for too long, these can sicken your fish and lead to an accumulation of aquarium mold. In addition, gravel is heavy enough that it doesn’t get pulled into the aquarium filters where it may clog them or cause them to work less efficiently. Gravel also comes in a variety of colors so you can customize your tank and make it complement your fish.
The Case for Sand Substrate
Sand substrate doesn’t allow water to flow through it as well as gravel does. However, if your tank includes fish that like to burrow and scavenge in the sand, they will do the job of filtering the substrate. Sand has a couple of other benefits when compared to gravel. Many aquarium owners think it looks more natural, better mimicking the lakes or riverbeds that make up fish’ natural habitats. In addition, closely packed sand substrate needs to be changed less frequently. Because there are smaller gaps between the sand particles than between gravel particles, old food and plant matter tend to stay on top of the substrate rather than sinking to the bottom where they can rot and decay.
Plant and Animal Considerations
Some plants and animals you may keep in your aquarium have strong preferences for either sand or gravel substrate. For example, many species of cichlids need sand substrate in order to thrive since eating particles of sand help them digest food. Goldfish, on the other hand, risk suffering from an intestinal blockage if they accidentally ingest sand and so should always be housed in gravel substrate. Aquarium plants also have preferences for sand or gravel, so make sure to research the needs of the plants and animals in your tank before committing to sand or gravel.
Placing and Changing Substrate
When placing substrate in your aquarium, make sure to use the right amount. Small to medium aquariums should have two to three inches of gravel or one inch of sand in the bottom. Larger aquariums should have three to four inches of gravel or two inches of sand. Substrate does not need to be changed on a regular schedule, but should be swapped out when it becomes slimy or muddy.
A number of factors go into deciding which type of substrate to use in your tank. Choosing the right substrate is essential to the health of the plants and animals in your aquarium.