How to Build a Fish Tank Sump Box

Sumps are external water storage unitsconnected to the aquarium's water system. This increases the total water volume of the aquarium and helps stabilize pH, temperature and salinity (for saltwater tanks). Many different containers can function as sumps, including aquariums and plastic bins from the hardware stores. If you decide to make your own, the easiest way is to use acrylic. Acrylic is easy to cut, bend and glue and you can usually find it in sheets at a hardware store.

Things You'll Need

  • Acrylic sheets
  • Fine toothed saw
  • Acrylic glue
  • Aquarium safe silicone
  • Propane torch
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Instructions

    • 1

      Plan the design of your sump. Draw this to scale on a sheet of paper, or use a computer design program. Don't haphazardly sketch it; draw carefully and measure each piece of the sump. The area where the sump will sit will determines the dimensions of the sump itself. Account for any plumbing that you will use.

    • 2

      Measure and cut out the base of the sump from the acrylic. This will determine how the rest of the sump fits together.

    • 3

      Measure the length of two or three walls of the sump. Add about an inch for each bend you will make in the acrylic. Bending the acrylic instead of gluing the sides together will make the sides stronger.

    • 4

      Using a blowtorch or a heating strip, bend the acrylic to form the walls of the sump. How many walls you can form by bending depends on the size of the acrylic sheet. If you use a blowtorch, keep the flame moving across the acrylic sheet to avoid melting it. Use a carpenter's square to make sure the angle is perfectly 90 degrees.

    • 5

      Glue any seams together. Use glue specifically designed for acrylic sheets. The glue melts and welds the edges of the acrylic together to form one piece. Make the edges of the acrylic to be glued together as smooth as possible; gaps will prevent the glue from working properly. The glue will hold in a few minutes so you can continue working, but it will take up to two days to cure fully.

    • 6

      Glue the walls to the base of the sump. Use the same procedure as when you glued the sides together.

    • 7

      After you build and glue the walls, add any baffles inside the sump. Baffles divide out areas of the sump for different purposes. Typical sumps have two sets of baffles. The first baffle divides the area where the water enters from the middle section. The next set of baffles divides the middle section from the return pump.

    • 8

      Glue the baffles in place.

    • 9

      Using aquarium safe silicone, add a layer of silicone to all seams inside the sump. This will help prevent leaks.

    • 10

      For added strength, add a lip to the top edge of the sump. This lip is simply a narrow length of acrylic glued to the top edge of the sump. It makes the sides stronger and will help prevent the sump from breaking.

    • 11

      Smooth rough edges with a blowtorch. The edges and corners of the acrylic can be sharp. Smooth them by going over them with a blowtorch.

    • 12

      In a safe place, fill the sump with water. Take it outside and fill it with water from the hose. Check carefully for leaks. If you find a leak, mark the spot, then add silicone to it after draining the sump.