How to Reduce Bubbles in Aquarium Sumps

The aquarium sump is a water reservoir separate from the aquarium. It's used as a convenience to hold additional equipment such as heaters and filtration units, and it's where you'll perform water quality testing. Basic sumps generally consist of the reservoir/container, a return pump and an overflow system. Sumps may develop an excess of micro-bubbles caused by air leaks or other mechanical problems. These bubbles can then enter the main tank via the return pump, obscuring the view of the fish and reef. You can remedy such a problem by investigating carefully and applying a few simple techniques.

Things You'll Need

  • Silicone adhesive
  • Glass or acrylic sheets for baffles
  • PVC pipe
  • PVC Y-connector
  • Bio balls, sponge or aquarium floss
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Instructions

    • 1

      Unplug the return pump and remove it from the sump tank. Locate the input and output pipe connections on the pump. Reseat the pipes on the pump to ensure they are holding securely. Test the connections by putting a bit of soapy water on them and blowing air into the pipes. The pipes will produce soap bubbles if the connections are loose. Air leaks from these areas can cause excessive bubbling in the sump. Use a silicone adhesive instead of glue to secure the pipes to the pump to prevent leaks from creating excess bubbling. Allow the silicone to cure completely before replacing the pump in the sump tank.

    • 2

      Install baffles in the sump basin with silicone adhesive. Baffles are a series of sections alternating walls in the sump tank that slow the water flow and reduce the amount of bubbles flowing through the system, according to the SaltwaterMasters website. To install baffles, empty the tank of all water and equipment. Cut glass or acrylic panels of graduated heights to fit into the inside of the sump tank and glue them at successive points, positioning them from the highest to the lowest as you move away from the overflow pipe. Use silicone adhesive to secure them into place. Then refill the tank.

    • 3

      Adjust the water overflow from the display tank to the sump. Large amounts of water overflowing from the main tank can cause excessive aeration and bubbling. In general, the return pump should move five times the volume of water in the tank per hour through the sump. For instance, the return pump on a 75-gallon tank should move at least 375 gallons per hour through the sump, according to Scott Zachow of the Reefland website. Your return pump's capacity should be indicated on the box it comes in, if not also on the pump housing.

    • 4

      Change the vinyl overflow tubing to PVC pipe to reduce bubbling. Vinyl tubing can trap air that leads to excess bubbling. Disconnect and remove the tubing from the overflow tank and return pump. Replace with a suitable-size PVC pipe. You may have to size down the PVC pipe to reduce the water flow enough to prevent bubbles from forming. Use a Y-connector pipe for the overflow if necessary to reduce water flow from the display tank. Glue the new pipe securely with silicone adhesive and allow to dry.

    • 5

      Install a filtering medium such as bio balls at the overflow tube to help to dissipate the bubbles. Bio balls are small plastic balls contained in nylon netting; they improve filtering and oxygenation in the tank water. Sponge or floss, available at aquarium stores, will also work, but these materials require frequent cleaning.