Autumn and Winter Maintenance
Cleaning and Storing Pond Equipment:
Consider draining the pond and thoroughly cleaning it if there is two inches or more of muck on the bottom. During this process, you should temporarily place any fish you have into a "kiddy pool holding tank" that contains water that has been taken directly from your pond. Before you return the fish to the pond, temper/adjust the "kiddy pool" water with the new water from the freshly-filled pond and add a dechlorinating product if necessary.
If there is less than two inches of muck in the bottom of your pond, you can simply net or vacuum out the debris. Something like a wet/dry ShopVac is a great way to "spot clean" dirty areas.
Clean the outside edges around the pond and place a temporary net over the pond surface to keep leaves from falling/blowing into the water. Be sure to use a net that has large enough holes to prevent frogs and birds from getting tangled in it and don't let the net dangle in the water if you have fish in the pond as they too might get tangled. Flexible PVC pipes (approximately 3/4" in diameter) can be used to keep the net out of the water (as seen in the photo below). Remove the net after the main leaf fall and before the heavy winter snows arrive.
Add "cold water" beneficial bacteria (e.g., Exotic Waterscapes Cold Temperature, MicrobeLift Autumn/Winter) as that will help reduce the buildup of dead leaves, as well as help "jump start" your pond in the spring.
Clean and store your filter pads from the pump, skimmer, waterfall filter, etc or consider buying new ones for next Spring.
Remove and clean all of your pumps and fountains and store them in an area that doesn't freeze. If the manufacturer recommends it, store them in a bucket of water to keep them well-lubricated.
Drain all of your hoses so that they don't crack from freezing water left in the lines. Cap the ends to also keep out mice, etc.
Remove and clean ultraviolet lights and store them in an area that doesn't freeze. Replace the bulbs each year or as often as the manufacturer recommends.
Fish and Plant Maintenance:
Switch to a low-protein, high-carbohydrate food for your fish when the water temperature drops below approximately 60 degrees. This food is easier to digest and allows the fish to start storing fat. Look for food that is wheat-germ based (e.g., Cheerios).
If you are going to move your fish or tropical plants indoors, make sure you do it before the temperature difference is extreme and definitely do it before the first frost of the season. Use pond water to make the transfer, as long as it is clean and disease-free.
Stop fertilizing your plants after September 1st. That will allow them to start storing energy for the upcoming cold season.
Once hardy plants turn brown and "die back," you can trim them down to a few inches and place them in the deepest section of your pond. However, we've learned that many hardy marginals will overwinter in this region without this additional protection, but a hard winter could kill some of your plants if they're left high in the pond. If you decide to take your plants completely out of the pond, you should also trim them back as described and allow them to go dormant by keeping them moist in a dark, non-freezing area. Otherwise, take your chances and hope for a mild winter!
If you don't have any hardy potted plants stored overwinter in your pond, leave at least one pot with soil in it in the bottom of the pond for frogs and snails to bury themselves in during the cold season.
Keep an area of the pond ice-free if you have any fish in it. This is necessary to allow for a proper gas exchange during the winter. Consider using either an air pump and an airstone or a floating heater that is thermostatically-controlled. Some folks get creative and use such things as a Frisbee (weighted down) with a piece of PVC pipe stuck through the center of it to create a pathway for gas exchange. A scrap of liner placed on the surface of the ice or snow can also be used to help melt a section, if necessary.
Things to NOT Do:
Do NOT run pumps or airstones more than a few inches below the surface of the water. You run the risk of "super-chilling" the water and injuring/killing any fish.
Do NOT "seal" the pond for the winter by doing such things as covering it with plywood and placing hay bales on top of the wood. You will literally kill all of your fish and many, if not most, of your plants.
Do NOT bang on the ice to clear an open area. You can injure/kill your fish with the resulting shock waves. Instead, use a pan of hot water to melt a small section of ice.
Do NOT completely drain your plastic performed-pond shells. By leaving a little water in them you actually give the unit some stability to resist heaving.
Do NOT feed fish once the water temperature drops below 50 degrees - no matter HOW much they beg!