If you are a pond owner in the northern climates where things freeze–up over the winter months, you will need to prepare your pond for these frozen times. In Southeastern Wisconsin we generally have winter like conditions from November through March. During these times our Northern ponds are in a state of hibernation with the water temperatures below 55 degrees and snow or ice accumulating in and around the ponds. During these times, the water garden both looks and acts very differently than it does during the summer months. We, as pond owners, need to prepare ourselves and our ponds for these winter months.
As winter approaches and temperatures start to drop, it is a good idea to monitor the water temperature so that you are sure to stop feeding your fish once the water temperature is consistently below 55 degrees. Below this temperature, the fish’s metabolism slows down and any food taken in takes a very long time to digest. If your fish have their bellies full of food when the water temperature drops, this food may stay in their system for too long and cause them serious problems. As the weather starts to get cold, you will notice the fish and the frogs in your pond will become much less active. The fish will gather together in the deep parts of the pond and move around very little. The frogs will also move around much less, and may only be seen on warm sunny days.
After the temperature and the leaves start to fall, and before the ice starts to form is a great time to get into your pond and clean up some of the debris and dead plant material that may have accumulated over the summer. You should also keep an eye on any tropical and floating plants which will die very quickly once the winter frost sets in. Try to get these dead or dying plants out of the pond before they sink to the bottom. Too much decaying matter in your pond will make the winter months harder on your fish. Having said that, I’d like to point out that this muck and/ or decaying matter is just the spot that your frogs will be looking for. They like to spend the winter buried in these debris laden nooks and crannies. Not to worry though, they can always bury themselves in the planting pockets with your water lilies. If your fish reproduced over the summer and you find your pond over populated, this would be a good time to give some of these little fish to friends or family who may have a place for them. Over-crowding will make it more difficult for your fish to survive the winter.
The fall is also the time of the year for you to decide how you will treat your pond for the winter. You need to decide if you will be able to monitor your pond and keep it running for the winter or if you will shut it down for the winter. Either way, you will need to turn off and disconnect your auto-fill valve before it freezes to prevent your plumbing, and/or the valve from being damaged. You may also want to consider installing some sort of netting over your pond to keep leaves and debris out of your pond while the skimmer is not functioning.
If you have fish in your pond, you will need to treat your pond differently than if you do not. If you don’t have any fish or frogs in your pond, or you have taken them out for the winter, you can just pull out the pump and let the pond freeze over. Your pump should be stored in a bucket of water somewhere where it will not freeze.
If your pond will be home to our wonderful underwater friends for the winter, then you will need to take steps to ensure their survival. The most important thing that you can do for your aquatic animals in the winter months is to keep a hole in the ice at all times to allow gasses to escape from under the ice so that the oxygen levels are not depleted. There are several ways to accomplish this.
If you want to shut your pond down for the winter, you will need to install a floating heater and/or an aerating pump. There are many types of heaters on the market; most are the old-fashioned high wattage tank-type heaters that radiate heat in all directions. These heaters do a fine job, but they use quite a bit of electricity. The new style of floating heater is a low-wattage heater that only radiates heat toward the center, to keep a small opening in the ice. These heaters are much more economical to run and, in most cases, will do a fine job of allowing the gases to dissipate from your pond. If you are using one of these low-wattage heaters, you may get a bit of ice forming over the hole if the temperatures drop below zero for too long, but a light tap will be enough to break this ice. If you have a very large pond, you may want to use more than one floating heater. The floating heater alone will most likely be adequate protection to keep your aquatic friends alive and well over the winter, but if they are considered family pets or if your pond is over-crowded, you may want to consider going one step further and also install a small aerating pump or bottom aerator in your pond which will bubble the water’s surface and provide additional aeration for the winter.
If you decide to keep your pond running for the winter, you have several options; just let it run all winter the same as it does in the summer, Install a winter bypass line, or install a winter return de-icer.
Depending on how your pond and waterfall/stream is laid out, you may want to simply let it run all winter. This will provide the needed aeration as well as keep the pond open for gasses to escape. Your pond can be absolutely beautiful during the winter months when you can see glimpses of your waterfall and stream through the ice and snow. If you choose to let your waterfall run for the winter, your pond must be monitored. There is always a chance that a clump of debris or ice will get caught in your stream and divert the water out of your pond, which may result in a damaged pump. Also, your pond water is still evaporating during the winter months and your auto-fill valve will not be working, so it is a good idea to keep a garden hose somewhere warm which will allow you to top off the water if it gets low. A short steep waterfall will be less problematic over the winter months than a long meandering stream as there will be fewer places for ice or debris to build up and less evaporation.
If you have a long stream and would like to keep your pond running for the winter, you can have your pond builder install a winter bypass line which would allow you to aerate and circulate your pond with out the worries of a long stream. This winter line would connect to your pump just like the line to your biofalls, but it would run into the very end of the stream or anywhere that it could provide water movement and aeration. You should be aware that it is possible to super cool the water in your pond by circulating the water too much over the winter. This can be harmful to the fish. They will be looking for calm, protected areas where the temperatures remain fairly stable. If your pond is over-circulated, which may happen if you have a small pond with a big pump, you may not leave them with a good place to spend the winter.
Another option would be to install a winter return de-icer. This de-icer hooks up to your current check valve in a matter of minutes. This attachment simply extends out over the top of your skimmer and directs the water flow onto the pond’s surface, which will keep an opening in the ice and keep the water aerated as well.
The choice is yours, you can shut it down and forget about it or you can keep it running and enjoy it. If you are going out of town a lot this winter, or simply do not want to go out in the cold and monitor your pond, you should shut it down and get a floating heater. But, if you will be around to enjoy and monitor it, an ever-changing winter water garden could be the focal point of your winter landscape.