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How to Keep Fish Alive and Maintain Your Winter Pond: A Complete Guide

    Ponds aren’t just for summer. As the temperature drops, you can look forward to watching your water feature transform into a wonderland of gorgeous ice formations and snow-covered waterfalls.

    We design our ponds, waterfalls and fountains to require minimal maintenance year-round, including in winter. All you need to do is take a few simple steps to protect your fish and plumbing.

    Want us to do the work for you? Splash Supply Co. offers a full range of seasonal services for water feature owners in southcentral PA and northern MD.

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    Top 10 Tips for Winter Pond & Fish Care

    1. Stop feeding fish in the fall and do not resume until water temperatures are consistently above 55 degrees
    2. Winterize automatic dosing systems before first frost. (See instructions here.)
    3. Prevent fish suffocation with an aeration system – this is HIGHLY RECOMMENDED for every pond, and CRUCIAL for ponds that have been shut down for the winter
    4. Cover the aeration compressor (the part outside the pond) with a Faux Rock Boulder Cover to protect against snow
    5. If the pump is off, remove the check valve (if you have one) and drain the water from the plumbing
    6. If the pump is on, watch for ice dams and snow that divert water out of the pond
    7. Remove any fall leaf nets before first snow
    8. Use fish caves and predator deterrents to give fish shelter until plant growth resumes
    9. Add Cold Water Beneficial Bacteria once per week
    10. Optional: Float a de-icer above the aeration diffuser for additional peace of mind

    Winter Pond Product Checklist

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    Do I Need to Shut Down My Pond in Winter?

    Winter waterfalls look amazing. That’s why we design our ponds to run year-round. Still, some pond owners prefer to shut down their ponds in winter for peace of mind, especially if they plan to travel for more than a few days.

    Why might you want to shut down the pond? Snow and ice can build up in strange ways, causing water to divert out of your stream.

    If you keep your pond running, you need to watch out for these kinds of issues and deal with them as they arise. You’ll also need to have a hose available to top off the pond as-needed, especially as the water starts to freeze (your pump can’t pump ice!).

    If you choose to shut down your pond, follow the steps below to protect your fish and plumbing.

    How Do I Winterize My Pond?

    The first step to winterizing your pond is to install an aerator. The force of the bubbling air will break the surface tension of the water and allow gases to escape, keeping your fish happy for the winter. (Even if you keep your pond running, you may want to install an aerator for additional oxygenation and as a backup in case your pump stops running.)

    The next step to winterizing your pond is to unplug the pump and drain the plumbing. Check out our winterization guide for more winterization tips:

    Live in southcentral PA or northern MD? Check out our professional winterization service:

    Will My Fish Be OK? Do I Need a Heater?

    Koi, goldfish and other common pond fish will survive the winter outdoors given the right accommodations. They conserve energy by entering a semi-dormant state called torpor. While in torpor, their metabolisms slow down, they stop eating and they might even lie almost motionless on the bottom of the pond.

    Stop feeding fish when the water temperature is consistently below 55 degrees. (We stopped feeding our fish at Splash a couple weeks ago.) You can gradually resume feedings in spring when the water is consistently above 55 again.

    You also need to make sure your fish have plenty of oxygen under the winter ice. Even if you keep your pond running, it’s never a bad idea to install an aerator over the winter to ensure your finned friends can breathe.

    Some people also like to install a de-icer for additional peace of mind. Always use a de-icer in addition to – and not in place of – an aerator. While the de-icer will keep a hole open in the ice, it won’t break the surface tension of the water, leaving bad gases trapped under the surface.

    (By the way, native turtles are also well-adapted to survive the cold – and the way they do it is pretty cool. Click here to learn more.)

    What Should I Do If My Pond Freezes Over?

    If your pond freezes over, you’ll need to make a hole in the ice ASAP so your fish can breathe.

    Here’s how:

    • Avoid smacking the ice. The vibrations moving through the water could harm fish.
    • Place a pot of hot water on the ice and watch it slowly melt through. (You may need to do this a couple times depending on the thickness of the ice.)
    • Turn a de-icer on its side on top of the ice. Our 300 Watt deicers typically melt through about 1 inch of ice per hour. (Your ice might end up 2 to 6 inches thick in extreme cold.)
    • Use a rough-toothed saw to cut a hole.
    Pond Deicer

    After you have a hole open, take steps to ensure it doesn’t refreeze. The best way to do this is by placing an aeration diffuser about 18 inches below the water’s surface. The bubbles will not only keep a hole open but also break the surface tension of the water, letting bad gases escape.

    For additional peace of mind, float a de-icer above the aeration diffuser. Use the de-icer in addition to – never in place of – the aerator.

    How to Install an Aerator for Winter

    Lack of aeration is one of the top causes of winter fish death. As ice forms on the pond, it traps bad gases in the water, slowly suffocating pond life.

    Aerators prevent this problem by 1) keeping a small hole open in the ice and 2) breaking the surface tension of the water. While a de-icer on its own will do the former, it won’t do the latter. That’s why we recommend running a de-icer in addition to – and never in place of – a proper aerator.

    (If you keep your pump on year-round, a running waterfall might also disturb the water enough to keep the pond oxygenated. But it never hurts to run an aerator too, or at least have one on-hand in case the pump fails).

    We like the Pro Air 20 Aeration Kit for ponds up to 5,000 gallons, and the Pro Air 60 for ponds up to 10,000 gallons. These heavy-duty aerators have cylindrical diffusers that give off a steady stream of bubbles, even if they get jostled in the pond. They’re also great for use in summer, when water has a hard time holding oxygen.

    To run your aerator in winter, lay the diffuser (the part where the bubbles come out) horizontally on a shelf about 12 inches under the water. Place a small TrueRock Boulder Cover on the compressor (the part that stays outside the pond) to protect it from ice and snow. The compressor and diffuser can stay here year-round if desired.

    If your aerator doesn’t seem to have as much power as it used to, clean the diffuser to remove buildup. Aerators also have rubber diaphragms inside the compressor that need to be replaced periodically. Replacement kits are available through our online store, or you can bring the unit to Splash for us to replace it for you.

    How to Use a De-Icer in Your Winter Pond

    A de-icer is a device that floats in your pond and heats the area immediately around it. It won’t raise the overall temperature of the pond (so your fish will stay in their semi-dormant torpor), but it will keep a small hole open in the ice to aid in gas exchange.

    A de-icer should always be run in addition to – and never in place of – an aerator. While a de-icer will keep a small hole open in pond ice, it won’t break the surface tension of the water.

    A de-icer can still be helpful to have for additional peace of mind in winter, especially on very cold days when the aerator or running waterfall might not be enough to keep a hole open in the ice. If you choose to use a de-icer, position it over top of the aeration diffuser or at the base of the running waterfall.

    Our de-icers are made of stainless steel and come with a three-year warranty – making them a little pricier than plastic models, but much more reliable.

    To get the most out of your de-icer, let it float in the pond for about an hour before plugging it in so the unit can calibrate to the water temperature. After plugging it in, you’ll see a blue light indicating that the unit has power. This light will turn red when the de-icer is actively heating (thermostatic controls ensure it’s only running when needing, helping save on energy costs.)

    You can also use a de-icer to melt a hole in the ice if the pond freezes over. Just place the unit on its side on top of the ice and give it a few hours to melt through.

    De-icers are available at Splash or through our Online Store.

    Can I Keep My Pond Running If It's Snowing?

    Wondering if you can keep your pond running during snow? For most people, the answer is yes, IF you’re able to check on it every so often. If you’ll be be away, though, you might want to disconnect the pump and check valve.
    If you decide to keep your pond running, keep an eye out for ice dams or snow that divert water out of the pond if the pump is still running.
    A few more things to keep in mind when it snows:
    ❄ If you have a leaf net over the pond, you should consider taking it down. The added weight of snow could collapse the frame.
    ❄ If your pond is running, have a non-frozen hose at the ready in case you need to top off the water in the skimmer. Your pump can’t pump ice!
    ❄ ENJOY! Ponds are just as pretty in the winter as they are in the summer. That’s one of the things that makes them better than a swimming pool!

    What If I Have a Disappearing Waterfall?

    If you keep your waterfall running, all you need to do is clear any dams created by ice and snow, and top off the waterfall basin as needed. Your pump can’t pump ice!

    If you need to shut down your waterfall for any reason, just unplug the pump. We design our Disappearing Waterfalls without check valves, so you don’t need to worry about water sitting in the pipe. (You may want to disconnect the threaded union inside the pump vault though if you plan to keep the waterfall off the entire season.)

    You do not need to drain the waterfall in winter. Your liner, basin, and pump vault are designed to handle freezing and thawing, regardless of whether the pump is running.