What grain size is best for aquarium sand?
For many freshwater tanks, medium sized grains (around 0.5 to 1 mm) have a good balance of natural look, comfort, and water movement. If you have bottom dwellers who sift or burrow, pick finer, rounded sand, but keep in mind that very fine grains can get stuck together and may clog your filter. A bit coarser sand, about 1 to 2 mm, can be better for rooted plants and tanks that use undergravel filtration.
How should I clean and prepare aquarium sand?
Start by rinsing the sand in a bucket that you've filled with water. Stir it well and then pour off the cloudy water. Repeat the process until it is mostly clear. Add the new sand to the tank, cover it with a plate or plastic bag while filling so there is less disturbance, and run your filter with fine mechanical media until the water is clear. Don't use soap or detergents, and be sure to dechlorinate the new water before adding fish to the tank.