Choosing aquarium gravel is more important in maintaining your aquarium than one might think. Gravel, or substrate, is the material that is used on the bottom of your tank. The substrate can impact not only your filtration system and water chemistry, but it also greatly impacts the well being of your aquarium's inhabitants. In choosing aquarium gravel, the first step is to decide whether you are going to have a saltwater or freshwater tank. All types of gravels do not work in all tanks. That is something that must always be uppermost in your mind when trying to decide what type of gravel to purchase.
For saltwater fish, the most popular substrates that are used are coral sand and coral gravel. Corals are popular for people when choosing aquarium gravel because they have a buffering effect on the pH of your water. They also emit calcium, which is important for some tropical fish. The presence of calcium should not cause any harm, however, to those fish that do not necessarily require great amounts of it.
If you have a reef aquarium, the substrate will have a very important effect on your water's chemistry. Coral sand is widely thought to be the best substrate for reef aquariums. Live rock can also be used as part of your substrate, and it has much the same effect that corals have in your aquarium.
In choosing aquarium gravel, you will want to carefully evaluate the benefits that your fish may receive from each type that is available for your particular aquarium. Keep in mind that choosing aquarium gravel is also important in the biological filtration processes of your tank. It is, in fact, a very necessary component of the entire process. For this function to work properly, the gravel (substrate) would be placed on top of a grate. The grate would contain one or more uplift tubes. Water is pumped into these tubes with either an air pump or water pump, forcing flow through the gravel. This procedure aerates the entire gravel bed. Good bacteria (not harmful) are then able to colonize in the gravel, which provides biological filtration. Filters under the gravel are generally used only in smaller aquariums, but can sometimes successfully be used in larger ones.
Remember, when choosing aquarium gravel for your saltwater tank, corals typically work best, but you should use whatever type you feel most comfortable with in your aquarium.
