Add dry beneficial bacteria when the water temperature stays about 45 degrees. When cleaning biological filters clean only the pads, not the media. Use pond water to clean the pads since tap water contains chlorine which will kill the bacteria. Spring maintenance includes removing leaves and organic matter. Expect a period of green water as the pond comes back to life.
Late spring is also the best time to add new aquatic plants.
Summer maintenance includes pruning water plants and keeping an eye out for insects or disease. Be sure to keep water level high and filters and strainers clean. Autumn maintenance includes cutting back plants and removing leaves and organic matter before winter. Winter maintenance's main activity is making sure the pond does not become completely covered with ice since the ice will trap gases which can kill fish. To keep an open spot in the ice you can use your pump as long as you never turn it off during cold spells.