How to Install an Overfill Drain in an Aquarium

An overflow drain supplies water to the aquarium's sump. Sumps are plastic or glass containers which stand below the aquarium. A sump increases the overall volume of water in the system and allows the hobbyist to hide unsightly pieces of equipment such as heaters, protein skimmers and power heads. Aquarium water runs through the overflow pipe to the remote sump, from where it is pumped back to the main aquarium. The sump is typically only filled to the halfway mark. Aquarium water will circulate continually through the sump for as long as the pump operates.

Things You'll Need

  • Aquarium with base pane, predrilled (0.72-inch hole)
  • Glass sump, 30-gallon
  • PVC pipe,18-inch (0.72-inch male thread)
  • PVC pipe, 12-inch (0.72 inch female thread)
  • 1 washer, 0.72-inch
  • Assistant
  • 1 Tube silicone sealer, non-toxic, 100 percent
  • Submersible pump, 180-gallon-per-hour
  • Plastic tube, 6-feet (0.2-inch)
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Instructions

    • 1

      Position the glass sump under the predrilled hole in the aquarium's base pane.

    • 2

      Squeeze a thin bead of silicone around the predrilled hole on the inside of the aquarium.

    • 3

      Place a washer over the threaded end of the 18-inch PVC pipe and gently push the thread through the predrilled hole in the base pane of the aquarium. Push down on the pipe to ensure the washer is flush with the glass.

    • 4

      Screw the 12-inch PVC pipe firmly into the 18-inch PVC pipe, from underneath the aquarium. Request that an assistant hold the vertical 18-inch pipe while you tighten the vertical 12-inch pipe from below. This union must be watertight or water will continually leak from the aquarium.

    • 5

      Squeeze a continuous bead of silicone around the washer (inside the aquarium) and smooth with your finger to form a watertight seal.

    • 6

      Allow the silicone to dry for 24 hours.

    • 7

      Push one end of the 6-foot plastic tubing onto the exhaust nozzle of the submersible pump and place the pump on the floor of the sump. Secure the opposite end of the plastic tubing over the aquarium rim, at the opposite end to the predrilled hole. Use a plastic clamp to secure this end to the aquarium rim.

    • 8

      Fill the main aquarium until water begins to flow into the vertical 18-inch PVC pipe. Allow the sump to fill to the halfway mark.

    • 9

      Turn on the submersible pump.