Filter systems should be sized near 1/3 of the water volume. When choosing a koi pond filter you are making huge decision for the future of your fish and your pond in general. Not only do they help to keep your pond water clear, they are responsible for removing organic waste and undesirable compounds from the water. In effect, the setteling Chamber and Biological Chamber on a Koi pond is really a small sewage treatment unit. If these wastes are not removed, your koi could get very sick and possibly die. With that in mind, here are some tips to help you choose the right koi pond filter. Do not get caught up all the advertising claims, these “Black Boxes” just can not deliver. Some provide zero filtration, some are mildly efficient but none can ever come close to the wishful performance claims made by manufactures. In just about every example, the small and totally inadequate box size completely hides what is really taking place. If total cleansing is required, (which is often do to size,) then the only real way to ensure that this is achieved is to manually strip the box down of all contents, wash them thoroughly and start again, usually with a complete loss of valuable bacteria. Sand filters are a nightmare and any bottle filter can never be cleaned completely, only diluted. All this is accomplished with an extreme waste of money, time and pond water.
Note: You must see the waste inside your system, and then you’ll know when to clean or when it is clean.
See this short video on how simple filtration is: