A backyard pond can be a real asset to any home, whether you stock it with koi, raise water lilies and other pond plants, or simply sit back and enjoy the soothing sound of a trickling fountain. But keeping the pond clean and the water clear can be a challenge. Make a homemade filter to keep your pond beautiful.
You can choose from two basic types of filters to keep your pond clean: a skimmer filter or a bio filter. Some people like to use both.
A skimmer filter, also known as a protein filter, screens out leaves, grass and other floating debris. To make a skimmer filter, you'll need a plastic container large enough to contain your pump. A plastic storage container with a lid makes a good container for your skimmer filter. You'll also need plumbing fittings for the inlet and outlet. These need to be attached to your storage container using fish-grade silicone. You can find this at pond and aquarium stores.
The pump should sit on the bottom of your container. Situate the water outlet on one side of the container and the inlet on the other side. You'll need some kind of filter material that sits below the inlet level. The idea is that the water comes into the filter, flows down through the filter, which catches debris, and goes through the pump and out. You can use any kind of material that won't rot in your pond, including pantyhose, nylon screen, fibreglass air conditioning filters or material especially made for ponds. The water must be able to flow freely through the filter, and you want something easy to clean, since you'll have to regularly clear away any debris it catches.
Sink the filter and let it fill with water, then put the lid on top and start your pump.
The second type of pond filter is the bio filter. A bio filter is home to beneficial bacteria that eat the crud that can cloud and contaminate pond water.
You construct a bio filter similar to a skimmer. But this time you want the water inlet to be at the bottom of the container, on the side opposite the outlet. Water will go into the container and up through the bio filter media. The bio filter media should be porous enough to provide a good home to the colonies of good bacteria you want to cultivate. Scrub brushes, plastic balls and even lava rock are good materials, but a sturdy, popular material to use is green fibreglass scrub pads made for industrial use. You can find these by searching online for "industrial green scrub pads."
Set your pump at one end of your container. Fill most of the rest of the container with your filter material. Leave some air space. Some people like to fill in with fine gravel or lava rock. This adds weight to the container and provides additional room for the bacteria to grow. Just make sure the gravel isn't small enough to be sucked into the pump.
Sink the filter and let it fill with water, then pop on the lid and start the pump. You'll need to periodically clean this filter also, but try to only sweep out the larger chunks of debris. Leave the dark "gunk" that accumulates in the filter material, as this is home to the beneficial bacteria.