Information on Salt Water Tanks & Live Rock Fish Filters

Salt water tanks require research, planning and expensive equipment. Live rock belongs in a salt water tank. Live rock tanks can contain fish only with live rock (called a FOWLR in the aquarium trade), or they might house a coral reef. Live rock contains beneficial bacteria that acts as a filter for salt water, turning dangerous ammonia into less harmful nitrates and nitrites.

  1. Water Conditions

    • Most live rock comes from Fiji, Hawaii and the Florida Keys, so conditions in your tank should reflect tropical marine waters. Successful live rock tanks contain water with a salinity of 32 to 37 ppt (parts per thousand) and a pH measuring 8.0 to 8.3. For corals to grow, you need a dKH (hardness) between 9 and 12 and calcium levels between 425 and 465 ppm (parts per million). The ideal temperature for a salt water tank varies depending on which species of fish and animal you keep, but most sea creatures in the aquarium trade thrive between 75 and 81 Fahrenheit.

    Equipment

    • Besides a glass or acrylic tank, equipment for a salt water set-up includes a mechanical filter (canister, overflow, drip or hang), a protein skimmer for waste removal, a thermometer and a heater and/or chiller (depending on where you live). Some aquarists purchase UV (ultraviolet) or Ozone sterilizers, which rid water of pathogens. Growing corals requires full-spectrum UV lighting. Some aquarists have their own reverse osmosis units, which they use to make freshwater to top off their tanks after evaporation.

    Stocking the Tank

    • According to Fishlore.com, a tank with live rock should hold 1 or 2 pounds of rock per gallon of water. Any fish that lives on or near a coral reef in the wild will do well in a live rock tank. Corals grow on or can be attached to live rock to create a coral reef.

    Live Rock Refugium

    • An aquarist keeping non-reef associated species of fish or especially delicate animals might decide to keep live rock in a small tank which shares water with the larger, main aquarium. Putting live rock in a small tank, called a "refugium," allows the tiny macroalgaes, amphipodes and copepods that grow in live rock to thrive. This method allows for the water-filtering benefits of live rock without taking up space in the tank with the fish.

    Curing Live Rock

    • All live rock must get "cured" before going in a fish tank. When live rock leaves the water for any amount of time, tiny organisms living within the rock die. "Curing" live rock removes the dying organism. Curing also helps remove harmful species like mantis shrimp and bristle worm that might be hitchhiking in live rock. Curing involves leaving rocks in saltwater for several days or weeks, gently scrubbing the rocks and changing the water daily.