So I get this question over and over and thought it would make sense to cover the basic processes that need to go on to prepare you pond for the winter time. First let’s cover what needs to be done before winter, preventative maintenance if you will. The first things we want to cover is filter cleaning, we will start with the skimmer.
First, you need to clean your skimmer filter and pump to ensure proper operation through the fall and winter months. This is accomplished by a few simple steps. First you will need to remove the skimmer net or basket, clean it and set it aside. Next remove filter pads that are situated between you and the pump, clean those as well (pressure wash if possible). At this point, if you are one of the lucky ones, you have a flap or door that covers the skimmer opening. Closing this will allow you to use the still-running-pump to empty the water out of the skimmer for easy cleaning. You can get the large debris that has collected in the bottom of the skimmer by simply letting the pump run until the skimmer is empty, unplugging the pump, and then removing all of the solids out of the bottom of the skimmer with your hands.
Check valves are simply devices that connect your pump to your plumbing with a back-flow preventer built into them. Check valves should either have a nut that you loosen by hand or a rubber coupling that comes off by using a screwdriver to loosen a clamp. Loosening the check valve will allow for easy pump removal. Be sure to un-plug the pump prior to loosening the check valve. NOTE: Loosening this connection will allow all of the water in your plumbing and biological filter to back-drain, so be careful not to get soaked and loosen slowly and expect water to drain out from above. Once the check valve has been separated completely, most skimmers will then have a support-rack that was holding up your filter pad, this may or may not need to come out with the pump depending on your skimmer and pump configuration.
Once the pump has been removed, ensure the inside of the skimmer is completely clean. Inspect the check valve for proper function and cleanliness. Faulty check valves are our the number one reason for pre-mature pump failures! You also need to inspect the pump. We normally make sure there are no blockages like gravel or sticks in the impeller of the pump by just spinning the impeller lightly with something other than your finger. It should spin freely without making any abrasive noises. This is the last step of skimmer maintenance other than putting it all back together. If you plan to run the feature during the winter, re-connect the check valve. If you plan to use aeration during the winter, we recommend storing the pump and check valve in a bucket of water in a protected area like a garage where it will not freeze. Do not store these items dry!
The next phase of winter preparation is cleaning out the biological filter or bio-falls filter. Your bio-falls should have been drained of water from the skimmer work so it is easier to clean at this point. If it was not, go ahead and drain it out as you remove all of the bio-balls, filter pads, and other biological media from your filter. Knock off the large chunks of organic matter from filter pads by banging them against a rock or such. These filters, along with your other media will need to be rinsed out with pond water in order to maintain biological function until the summer-time bacteria all goes dormant. City water is a no-no! If you are closing the pond down for the season, go ahead and pressure wash these filter parts and then put them back. We normally place some stones on the filter components to keep them in place once the system begins running again.
The final “work” of winter preparation is cutting back the plant material in your feature. Deciduous aquatic plants should be pruned back to prohibit unwanted biological mass from sinking into the pond, decomposing, and creating water quality problems in the winter months. Lily pads should be cut down close to the crown of the plant and other plants are cut back to just-above-water-level. You should also use a net and scoop as much of the leaves and bottom debris out of the feature as possible.
You are now ready to either install your aeration for winterization or to start the system back up. If you plan on running the system through the winter months, cold-water-beneficial bacteria is highly recommended for the health of your ecosystem. Also remember to follow feeding instructions based on water temperatures and do not feed fish if your ecosystem is winterized. I recommend that you have a conversation with a pond professional prior to shutting down a system and using aeration to be sure you understand and are comfortable with what that means!
Happy Pondering :)
John G Adams
John Adams is a professional pond artist and builder.