How to Make Saltwater for Hermit Crabs

Hermit crabs are marine invertebrate animals, but although they come from the sea, natural seawater is not always the ideal medium in which to keep them. Natural seawater contains disease-producing organisms or pathogens. It also contains plankton, which begins to die once the water is collected and stored. Natural seawater is also impractical to collect and transport and has often been exposed to human-generated pollution. Aquarists can, however, use synthetic sea salt to make seawater of a high quality for their hermit crabs.

Things You'll Need

  • 40-gallon aquarium
  • Garden hose
  • 3-oz. bottle of chlorine neutralizer
  • 50-watt aquarium heater
  • Small submersible pump
  • 3 lbs. of synthetic aquarium salt
  • 5-gallon plastic bucket
  • Hydrometer
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Instructions

    • 1

      Fill a 40-gallon aquarium with tap water. Use your garden hose to fill the aquarium with ease. Add three oz. of chlorine neutralizer to the aquarium and stir vigorously for a few minutes.

    • 2

      Place a 50-watt heater into its bracket and place it in the aquarium. Use the suction cups on the bracket to fix the heater against the back glass pane of the aquarium. Place a submersible pump in the aquarium.

    • 3

      Set the thermostat on the aquarium heater for 79 degrees Fahrenheit. Plug both the aquarium heater and the submersible pump into a wall power source and turn on the power.

    • 4

      Add three lbs. of synthetic aquarium salt to the aquarium.

    • 5

      Allow the aquarium water to circulate and heat up for at least 24 hours before adding the hermit crab to the aquarium.

    • 6

      Test the specific gravity of the water with a hydrometer or a refractometer to ensure that you have mixed sufficient salt with the water. You want a specific gravity reading of 1.025. This is a unitless reading.

    • 7

      Change 10 percent of the aquarium water on a weekly basis to dilute toxic metabolic products that have built up and to replace trace elements taken into the body of the hermit crab and other residents of the aquarium.

    • 8

      Prepare the replacement water at least 24 hours before use. Place a heater and submersible pump into the bucket in which you make up water so that the synthetic salt can mix thoroughly and the water can reach the correct temperature before it's added to the aquarium.