External pond pumps are great for large ponds with a bottom drain. In Koi ponds because of the large volume of waste it is a great idea to go for a gravity fed bottom drain which means all the debris that accumulates on the bottom of the pond is sucked into the refuge pipe. Ensure that your filter chamber is kept at the same water level as your pond water, that way the water is continually moved from the filter to the pond and from the pond to the filter.
Having an external pump is a cleaner way of pumping water out of your pond as it means all of the sludge at the bottom of your pond is naturally managed. This type of pump is not placed within the pond, due it’s large size. They can be installed into the ground next to the pond however and pump out water from the filter or other devices. Sturdy and solid in design, these units are designed to last and offer outstanding results year after year.