DIY Wet Dry Filters

A wet-dry filter employs a slow but steady trickle of water over filter media filled with beneficial bacteria. These bacteria turn deadly ammonia in fish waste and decaying matter into less toxic compounds called nitrites and nitrates. At the bottom of the filter is a sump from which the filtered water enters the aquarium.

Things You'll Need

Drill
Plastic tub or acrylic container
Inflow and outflow pipes or tubes
2 pumps
2 trickle plates
Hard filter media
Filter floss or polyester

Instructions

- 1
  Drill holes for inflow and outflow pipes or tubes into a plastic tub or acrylic container. Make the inflow at the top of the container and the outflow at the very bottom.
- 2
  Place a pump at the bottom of container to send water out the filter through the outflow tube or pipe back into your aquarium.
- 3
  Fit an acrylic sheet with holes (about one 1/8-inch hole every 1/2 inch) securely about two-thirds of the way down in the container, so that it is above the outflow. This is called a trickle plate.
- 4
  Fill one-fourth of your container on top of the trickle plate with nontoxic, nondegradable objects such as bio balls (a product specifically created as filter media), lava rock, chunks of natural sponge, steel-wool pads (soap-free) or even plastic hair curlers. These objects provide nooks and crannies and surface space for beneficial bacteria to grow. Whichever you choose, make sure the products are safe for your pond or aquarium.
- 5
  Place a layer of filter floss or polyester sheeting on top of your bio balls or equivalent filter media. The water will make contact with the filter floss before the hard media to remove any large debris such as bits of decaying leaves or uneaten food.
- 6
  Fit a second trickle plate several inches above the filter floss or polyester sheeting, below the inflow.
- 7
  Add a pump in the aquarium to pull water from your aquarium or pond into your inflow hole.