How to Change Aquarium Gravel

Decisions about aquarium gravel are often made after much of the budget has already been spent. And yet, this tank component can have a major effect on the health of your fish. Different substrates can raise pH (crushed coral), provide camouflage to a shy fish (darker colored gravels) or injure the delicate barbels of a catfish (rough gravel). If you decide that it is time to change the gravel, you will need to take into account the stress that it will cause to your fish and the beneficial bacteria that live in the gravel.

Things You'll Need

  • Holding tank
  • Air pump
  • Airstone or sponge filter
  • Water conditioner
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Instructions

    • 1

      Rinse your new gravel in order to remove debris which could cloud the tank.

    • 2

      Prepare a holding tank for your fish to stay in during the gravel change. This can be much smaller than their normal tank as your fish will only be there for a few hours. Use an air pump to power either a sponge filter or airstone for aeration.

    • 3

      Drain approximately half of the water from your fish tank. The goal is to remove as much water as possible in order to make it easier to net your fish.

    • 4

      Remove fish, plants and decorations and place them in the temporary tank.

    • 5

      Drain as much of the remaining tank water as possible. This is for your convenience when adding new gravel so you can leave as much as an inch without causing problems.

    • 6

      Scoop up the gravel with a plastic cup. Be careful not to scrape any gravel against the side of the tank. If possible, leave a small amount of the old gravel on the bottom in order to preserve the biological balance of your tank.

    • 7

      Add new gravel by cupfuls to avoid scratching the sides. Once you have a pile of gravel approximately 2 inches high and 6 inches around, you can pour in the rest. Aim for an average depth of 2 inches (see Resources section for more information).

    • 8

      Add new water, making sure to use a water conditioner to remove chlorine as well as adding aquarium salt and any other pH conditioner or plant fertilizer which you would normally use during water changes.

    • 9

      Wait at least an hour before returning fish to your tank in order to allow the water to clear. Add decorations and plants first and then your fish. Make sure to test the water a few days later and provide frequent water changes as the tank bacteria reestablishes itself on the new gravel.