This article is courtesy of Lynda Amm.
Spring:
Check pond's edges for any shifting or settling. Repair if necessary. Check electrical connections and make sure pump and filters are in good working order. Clean out all pond debris that collected over winter. Once temperature is above 50F, start biolgical filters (it will take beneficial bacteria several weeks to re-estabilsh.) Divide and trim plants and remove damaged parts. Re-pot plants in new pots or baskets if required. Position free floaters first, then submerged plants and then deep water. Check to make sure fish are okay. Fertilize lotuses with pellet fertilizer twice a month. Fertilize water lilies with pellet fertilizers once a month. Reposition marginal plants. Late spring is a good time to add new aquatic life.
Summer:
Check water once a month to keep track of pH, Ammonia & Nitrate levels. Check to see that plants and fish look healthy. Replenish water - top off the pond about an inch at a time. In very hot weather set the hose by the pond and let it trickle in slowly and continually. Remove yellowed foliage, faded flowers and thin if needed. Inspect pump once a week and clean if necessary. Spray aphids with water hose, remove larger insects. Increase fertilizing of lilies to twice a month when weather gets hot. Remove Blanketweed (and algae) in hot weather by twirling a stick and it will wrap around it - add to compost. Thin out any overgrown oxygenators and other floaters.
Autumn:
Keep leaves out of pond by putting netting over the pond and weigh it down with rocks. Use a net to remove any leaves that may have gotten in. Remove any debris that is on the bottom of the pond. Thin and cut back submerged plants. Cut back other aquatics as they go dormant. Trim water lilies to an inch above the containers. Remove tender aquatics and store them for the winter. Gradually taper off feeding the fish to once every 2-3 days.
Winter:
Protect pond from ice damage in short term freezes by covering it with a tarp and some boards. Keep ice from causing pressure on the sides of the pond by floating plastic milk jugs against them. The easiest way to keep the pond ice-free is to buy a floating pond de-icer - they are controlled by a thermostat so they run only when needed. Keep snow off the ice surface to allow light to reach the bottom.
Plant Types Defined:
Marginal:
Absorbs nutrients in fish waste that otherwise feed algae growth. Water depth 6-9 inches.
Deep Water Aquatic:
Prevents algae build-up, provides shade and shelter for pond life. Absorbs nutrients from fish waste. Planting depth should be suitable for size so that leaf and flower come out of water.
Submerged:
Essential to maintain clear, well-oxygenated water. Provides cover for wildlife in which to breed and shelter. Absorbs carbon dioxide to produce oxygen to replace oxygen used by fish. Competes with algae for nutrients. Water depth - maximum 3 feet.
Free-floating:
Prevents algae build-up by blocking sun. Provides shade and shelter for water life. Floats on surface.
References Used:
Complete Guide to Water GardeningComplete Guide to Water GardensWater Gardening