In pond filtration, pond pumps are very important. The size of the pond pomp will determine if it’s going to be a clean pond or a dirty one. An ideal pond pomp should be able to pump the whole pond volume at least once per hour or depending on how much fish there is. There are two types of pond pumps, the external and the submersible. External pond pumps are recommended if you have a larger pond because they are easy to maintain and are more energy efficient. Submersible pond pumps on the other hand are more appropriate for small ponds and water gardens.