The pond pump is the life blood of any koi pond or koi watergarden. Whether building a new pond or replacing an existing pump, there are many choices when it comes to buying a pump. There are also many things to consider when choosing the type and size of pump to purchase. Most koi ponds have a skimmer for handling mechanical and some biological filtration. This is where the main pump is usually located and provides most if not all the water movement for the entire pond. The pond can have more than one skimmer or the skimmer may have more than one pump depending on the size and shape of the pond. There can be a stream or water fall or a combination. An external filter or protein skimmer may also be involved.