How to Set Up a Filter for a 125 Gallon Fish Tank

Fish tanks are a contained, decorative way to bring nature into your home. People start large and small fish tanks for both fresh and salt water, to fill them with a range of colorful marine animals and plants. One of the most important aspects of the tank is water quality, and therefore filtration. Pump and filter systems pull water in, filter it and then push it back out into the tank to maintain that quality for the fish. For a large tank, set up a large pump and filter system to support the entire tank.

Things You'll Need

  • Pump and filter
  • Substrate
  • Decorations (rocks, plants, etc.)
  • Heater
  • Thermometer
  • Water (salt or fresh)
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Instructions

    • 1

      Purchase a pump and filter system that has a capacity of 125 gallons or more. The capacity tells you how much water the pump and filter will process. It's vital that your systems process your entire water capacity. If you can't find a large enough system, consider purchasing two smaller systems to handle your entire tank.

    • 2

      Add your substrate (sand, gravel, etc.), rocks, plants, thermometer and heater to the tank first. Now set up the pump and filter. Open the package and locate the pieces per the instructions, which should be included. Set the pieces up in your chosen location in the tank. A back corner is a good place to "hide" the equipment. For most pump and filter setups, the extension cord will attach to the pump, with a hose that connects the pump to the filter. There might be two outlets on the pump, so make sure that you attach the hose to the "out" connection. The pump will pull water in and then push it through the hose and through the filter. Do not turn your system on yet.

    • 3

      Fill the tank with either fresh or salt water, depending on what kind of tank you want. Turn the pump and filter on only after they're under water. Allow the system to run for at least an hour, to clean the water of debris, before you add any fish or other marine life.