Cleaning aquarium gravel is best done during regular water changes using a gravel vacuum, also called a siphon. This tool removes debris trapped between gravel pieces without taking the gravel out of the tank or disturbing your fish excessively.

A gravel vacuum consists of a wide tube attached to flexible hose. To start the siphon, submerge the wide tube in the tank and either use a pump bulb, a self-starting mechanism, or the classic method of sucking briefly on the hose end to get water flowing into a bucket placed below the tank.

Push the wide tube into the gravel about halfway down. The water flow lifts lighter debris and waste up through the tube while heavier gravel falls back. Move the tube across the substrate section by section. You do not need to vacuum the entire bottom each time. Cleaning one third to one half of the substrate per water change spreads the disturbance over several sessions and preserves beneficial bacteria colonies that live in the gravel.

Never remove all the gravel to wash it under tap water. Chlorine and chloramine in tap water kill the beneficial bacteria responsible for your nitrogen cycle, potentially crashing your biological filtration and causing dangerous ammonia spikes.

For sand substrates, hold the vacuum tube just above the surface and let the water flow pull up debris without sucking up sand. Light stirring of the top sand layer before vacuuming helps release trapped gas pockets.

In planted tanks, vacuum only open areas between plant clusters. Avoid disturbing root zones where plants are feeding from the substrate. Some planted tank keepers skip gravel vacuuming entirely and rely on plants to absorb nutrients from decomposing waste.

Aim to vacuum during your weekly water change so you combine two maintenance tasks efficiently. Consistent gravel cleaning prevents the buildup of decaying organic matter that fuels algae and degrades water quality.