A pond filter circulates healthy bacteria into a pond. These bacteria transform ammonia left in the pond into nitrate. Ammonia is caused by decaying fecal matter, left over food and other organic substances. Healthy bacteria are immersed into the pond as the water is pumped through the filter. Cleaning of the filter should be done on a limited basis as it disrupts the natural and necessary bacterial growth in the pond.
Monitor filters to see if cleaning is necessary. Clean the filter only when an obstruction of water flow is occurring. Many times the filter may need to be cleaned after the winter months. Cleaning the filter in the early spring gives the natural bacteria enough time to repopulate. A fall cleaning may be needed if leaves and other matter fall into the pond, releasing harmful substances and filling the pond with debris. The more mature a pond's water filter becomes, the more natural and healthy bacteria are released into the pond.
Remove the filter and place into a bucket of pond water. Do not use tap water. Tap water contains chlorine which will kill the natural bacteria.
Take apart the filter and find the obstruction. Only clean the areas that are preventing water flow. Using a small brush, look for algae and other material and remove. Replace any worn out or shredded pieces of the filter. Pads and sponges should return to original colour when rinsed---if not, replace.
Reassemble the filter and test. Make sure no leaks or obstructions are occurring. Test the pond water and replace any bacteria that may have been lost with bacterial additives found at pet or pond supply stores.
Ensure that the pond has a balance of natural plants and fish as well as flowing water.