A pond filter is an important component for any outdoor or indoor garden pond. Filters provide biological and mechanical filtration, drive the water through a filter medium and expel cleaner water free from ammonia or other waste from plants or koi. A good filter not only keeps water healthy but also keeps it clear. Dust filters vary in price from one hundred to several hundred dollars, but you can build your own with a trip to the iron business that is equally effective.
Cut several dozen holes in the side of plastic dustbin using a drill and a 1-inch hole cut the drill bit. These are the holes through which the water passes through when filtered. Place a 2-inch thick layer of pebbles on the bottom of the waste container. The pebbles weigh the filter and give surface to beneficial bacteria. Place a layer of plastic balls over stones. The balls give more surface area for the beneficial bacteria to grow. Place the bag of coal over plastic balls. The carbon helps to neutralize odors and harmful chemicals in the water.
Fill the rest of the trash with filter floss, which catches large particles that pass through the filter, and attach the lid tightly. Seal one end of the PVC hose to one of the holes on the filter you made using the aquarium sealant. Allow at least 24 hours to dry. Connect the other end of the PVC hose to the inlet pipe of the pond water pump. This is where the pump takes in water. Attach the two tubes using a tight-fitting rubber coupling. There should be about 6 inches of space between the filter and the pump, so you may need to cut PVC tubes with scalpel.