Proper filtrationfor the koipond is essential for the health of the fish and also the pond itself. It can make the difference between a green pondl laden with algae and a high fish mortality rate. Good mechanical filtration removes organic debris from the pond before they can break down and foul the water. Good biological filtration removes harmful amonias and nitrates that are harmful to fish and cause an algae outbreak. If you are not sure what filtration you need, give us a call and we will be happy to provide advise.