How to Make a Skimmer Outside of a Sump

One of the easiest ways to attach a protein skimmer outside of a sump or aquarium is to use a hang-on-back (HOB) skimmer (also called hang-on-sump, hang-on-tank, or hang-on-side). These are particularly useful if you have a small sump that cannot hold the skimmer. Some skimmers can be placed in the sump but come with attachments for installing it on the outside as well. To do this, you will need to find an edge of the sump sturdy enough to hold the weight of the skimmer when it is full of water.

Things You'll Need

  • Protein skimmer
  • Sump
  • Knife
Show More

Instructions

    • 1

      Attach the hanging clamp to the skimmer. These usually slip on over the bottom but might also come in two parts that you have to screw together. The clamp looks like an inverted "U" and will fit over the edge of the sump.

    • 2

      Hang the skimmer on the sump so that the hoses and pump all face in toward the sump. The skimmer will have an inlet pump (possibly with an overflow box) and an outlet hose that can be connected to a bubble trap or bubble filter such as a sponge. These both go in the sump.

    • 3

      Adjust the supports on the bottom of the skimmer so that it tips inwards to the sump about five degrees.

    • 4

      Place the water pump where you want it, then attach the airline tube to the venturi valve. The venturi valve is a special valve that will suck in water through the main water inlet and a bit of air through the airline tube. The air and water will be mixed by a special impeller in the pump.

    • 5

      Attach the outlet box inside the sump downstream from the pump. You can re-skim the water but it will reduce the amount of untreated water being taken in by the skimmer, which can reduce your filtration effectiveness. Often the boxes for the skimmer's outlet tube hang on the sump as well. If this is the case, make sure you have it on the inside of the sump.

    • 6

      Cut the tubing and attach it to the skimmer. The pump should be attached to the inlet at the bottom of the skimmer. The outlet should go into the bubble filter box.

    • 7

      Attach the collection cup and cap to the top of the skimmer. These usually have a gasket that you can tighten to form a watertight seal. Do not use a wrench.

    • 8

      Turn on the skimmer and adjust it so that the bubbles come just to the base of the collection cup. Skimmers have a valve on the outlet tube that you can close or open. Closing the valve will raise the bubbles and water level in the skimmer.

    • 9

      Check the skimmer frequently over the next several days and make necessary adjustments. As the skimmer builds a bio-film inside the reaction chamber, the bubble level will change. Make small adjustments to ensure it is skimming properly.