How to Install a Saltwater Aquarium Sump

Written by kasandra rose
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How to Install a Saltwater Aquarium Sump
A sump increases the number of fish you can place in your saltwater aquarium. (exotic fishes image by Vita Vanaga from

Sumps are a great way to hide the equipment needed for a marine aquarium, reducing the mechanical clutter in your tank and increasing its visual appeal. Sumps increase water volume, diluting waste and increasing the livestock capacity of a saltwater aquarium. They are easily converted to refugiums for further filtration capacity at a later date.

Skill level:

Things you need

  • Overflow box
  • 1- and 2-inch tubing
  • 5- to 10-gallon aquarium
  • Protein skimmer
  • Carbon filter bag
  • Thermometer
  • Aquarium heater
  • Return pump
  • Check valve

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  1. 1

    Set up the small aquarium below the saltwater tank.

  2. 2

    Insert your heater, thermometer, protein skimmer and charcoal bag into the small aquarium. Position the charcoal bag under the inflow to filter large particles and reduce the incoming water's splash.

  3. 3

    Install the pump. The pump will won't reach its overall rating because of the distance it must push the water vertically--you'll have about a 500-gallon-per-hour pump on most setups. Add an adjustable cut-off valve to the outflow tubing to ensure you don't pump too much water into the main tank and overflow it.

  4. 4

    Add a check valve above the pump to prevent the return tube from draining water from the saltwater tank, in case of a power failure.

  5. 5

    Fill the sump half full with saltwater and let it stabilise overnight.

  6. 6

    Attach tubing to the overflow box, leading down to the sump. Put the pre-filter on the connector in the overflow box.

  7. 7

    Prime the overflow box so water flows from the aquarium to the sump.

Tips and warnings

  • If your sump is gurgling air, insert a small air line into the gravity tube from the overflow, leaving the other end in the open air. This will produce quiet free-flow of air, instead of loud gulps of air being pulled into the tube.
  • Always ensure electrical connections have a drip U below the level of the electrical plug to let water drip off the cord before reaching the outlet. This means the cord drops below the outlet's level and then comes back up to the outlet, where you plug it in.
  • In case of power failure, check that your overflow hasn't lost its prime. If it has, turn off the return pump.

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