Do I Need to Replace Aquarium Rocks After Old Ones Are Removed?

A properly equipped aquarium includes many parts, one of which is gravel or substrate. When you remove old gravel, replacing it with new rocks or cleaning and replacing the old gravel is recommended for many reasons. Which substrate you use in your aquarium is up to you, whether that is rocks, sand, marbles, gravel or another material.

  1. Functions of Substrate

    • There are many reasons to have a substrate in your aquarium. One reason is to provide orientation for the fish. If there is no substrate the bottom of the aquarium is a reflective glass surface. The light from the hood bounces off the glass bottom and the fish can't tell where the top or bottom of the tank is located. Substrate is necessary for under gravel filtration. Substrate keeps the balance of the aquarium, housing the good bacteria that help reduce waste. The substrate also provides anchorage for plants and decorations and gives breeding fish a place to lay eggs and dig.

    Types of Substrate

    • The type of substrate you choose depends on what else you plan to put in your aquarium. Gravel, rocks and marbles are all simple to clean. Sand and other small-particle substrates work well with plants, but conventional cleaning methods don't work with the small particles. Large rocks and marbles allow eggs to drop through the crevices and remain unmolested by other fish. Heavier substrates help anchor artificial plants to the aquarium floor. Real plants need two layers for best results -- a bottom layer with nutrients for the plants and a heavier top layer to anchor the roots.

    Aesthetics

    • Substrates are part of the overall visual appeal of the aquarium. Gravels and sands come in many colors so you can color coordinate with the other decor of your house, or choose gravel colors that set off the coloring of the fish in the aquarium. Large rocks and marbles are pretty to look at by themselves and look even better lit in water. Sand or brown gravel with river rocks complete a natural look, especially when combined with plants and driftwood.

    Cleaning Substrate

    • Gravel and larger rocks and marbles are simple to clean without removing them from the aquarium. Use a simple gravel vacuum with a hose to vacuum the waste from the gravel or rocks. Move the vacuum around the bottom of the aquarium until you start getting clear water instead of brown waste. If you remove the gravel for cleaning, agitate the gravel while you rinse it in cold water until the water runs clear. Decorative sand should be stirred occasionally to get the waste into the water where it can be filtered out. If sand is too dirty, siphon it out over time as you do water changes and replace it with clean sand.