DIY Sumps for Aquariums

Many saltwater aquarists, and a growing number of their freshwater kin, swear by sump filters. Also known as trickle, wet-dry, or drip filters, these filters are renown for their biological filtration. They are someone unusual compare to other fish tank filters in that they tend to be designed and assembled by the end user, rather than purchased pre-made. This DIY aspect is both a boon, as it can be more cost-efficient to buy your own filter, but somewhat intimidating to less handy hobbyists. However, with focus and effort, it is not beyond most people's ability to create such a filter.

Things You'll Need

  • Suitable sump (second fish tank, or watertight glass or acrylic box)
  • Marker
  • Overflow box
  • Vinyl tubing (length and diameter varies with design)
  • Square glass or acrylic plates
  • Aquarium silicone (aka marine silicone, aquarium glue)
  • Filter media of your choosing
  • Secondary filters, skimmers, and heaters
  • Return pump
  • Return spigot
  • Check-valve
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Instructions

    • 1

      Check your sump for leaks. The best way to do this is to fill your sump with water, mark the water level with a marker, and cover the top. If the water level is the save after 1-2 days, the sump is watertight.

    • 2

      Install the overflow. This varies with the design of your overflow and sump. The simplest overflows are premade acrylic boxes that hang on the aquarium.

    • 3

      Attach a length of vinyl tubing to your overflow. It should be long enough to reach the "in" side of your sump.

    • 4

      Install baffles. Baffles are plates of glass or plastic that force water in the sump through various filter media. The simplest way to install them is to glue them in place with aquarium silicone. Allow it to dry for at least 24-48 hours; aquarium glue releases unpleasant chemicals while curing.

    • 5

      Add filter media to baffles. This will vary depending on how you set up your baffles and what filter media you choose.

    • 6

      Install any secondary filter, skimmers, and heaters in the sump. One of the perks of a sump filter is that you can have all of this unsightly equipment out of sight and out of mind.

    • 7

      Run a length of vinyl tubing from the return pump to the return spigot. Place the return pump in the "out" end of the sump and attach the return spigot to the back of the tank on the opposite side from the overflow box.

    • 8

      Cut the return tubing in half. Then, reconnect the halves with a check-valve. This will prevent back-siphoning, which can cause flooding.

    • 9

      Fill the sump with water, prime all pumps and filters. Then, turn on the return pump. Once water starts coming back in from the overflow, mark the water level on the outside of the sump with a marker. Do not fill the sump above this line when the return pump is running.