To sustain a balanced healthy pond, do as little cleaning as possible.
As the weather warms up, pond owners are often itching to get out there empty the pond, scrub the sides and give the filter a really good hard clean, thinking they are doing a very important service, this is often detrimental.
Ponds can take up to a year to create a balanced micro system, crucial to a healthy pond, stripping and cleaning your pond and filter will remove the good bacteria, which in turn can take many months to build back up again, not to mention the stress on the fish during the cleaning process.
Obviously removing fallen leaves and debris with a net is a good idea, clean filters only when the water flow is reduced, and only one or two of the filter mats at any one time, (filters with back washes can be done as often as you like).
Ponds with a thick layer of fine gravel on the base, a good filtration system and the right amount of fish (the more fish you have the less algae) should be relatively maintenance and cleaning free.
Article published in Garden Guru Magazine Spring 2009