Instructions
Using gravel is the most common way of covering the bottom of an aquarium. It comes in many colors and sizes. Keep in mind that dark gravel better highlights the colors of your fish.
Try sand as well if you aren't using an undergravel filter. Sand may clog a filter, so ask your fish dealer about the compatibility before using.
Be careful when using coral, sea shells and limestone. They release chemicals into the water that may harm fish.
Use crushed coral, dolomite or argonite in a saltwater tank instead of gravel. They are calcareous and good for the marine environment.
Wash your ground covers thoroughly before putting them into the tank by putting them in a bucket and running warm water through them. Stir up the water to get the impurities moving around. Keep rinsing until the water runs clear.
How to Choose Ground Cover for an Aquarium
Yet another consideration for the new aquarium enthusiast.