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What is supercooling? | Ponds & Lakes Q&A

Q: What is supercooling??

Q: What is supercooling?

Aloma, Warroad, MN

A: Supercooling is uncommon, but it can occur in lakes and ponds, particularly in the northern states. Here’s what you need to know about it and how to prevent it from happening.

In the winter time water stratifies in pond and lakes without proper aeration when surface temperatures are extremely cold, creating what’s called a thermocline. A thermocline happens as warmer water about 39°F or so – sinks to the bottom, while colder water about 32°F or so – rises to the top. Very little mixing of the layers occurs, particularly in calm weather.

Supercooling could become an issue if you’re running a surface aeration system in shallow ponds with fish. The fish prefer to stay on the bottom of the pond in the warmer pockets of water during the winter. They’re in winter-hibernation mode, and all they want to do is be in a stress-free spot until spring.

As the aerator circulates the warmer water with the cooler water at the surface, the overall temperature could drop. In extreme cases when the temperatures are well below 0°F, the water temperature can actually drop below its freezing point without becoming a solid – a rare process known as supercooling.

If the water gets too cold, your fish have nowhere warm to go. Living without their warm hangout spot could compromise their oxygen supply and immune systems, making them vulnerable to parasites and diseases.

The best way to deliver oxygen to your fish is with a bottom diffused aerator, like an Airmax® Aeration System. You can keep it running without creating an inhospitable environment for your finned friends by simply moving your diffuser plates closer to the surface or turning half of them off.

If you relocate the diffuser plates to a spot that’s about half the depth of your pond or run only 50 percent of them, a pocket of warm water will remain for your fish at the bottom. You’ll continue pumping oxygen into the water and keeping a hole in the ice for gas exchange without having to worry about freezing your fish.

Pond Talk: What steps do you take to prevent over cooling or supercooling your pond?

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Do I need to do anything else to prep my pond for winter besides moving my air stones? | Decorative Ponds & Water Gardens Q & A

Q: Do I need to do anything else to prep my pond for winter besides moving my air stones?

Q: Do I need to do anything else to prep my pond for winter besides moving my air stones?

Melinda – Novi, MI

A: Your to-do list of fall- and winter-prep chores isn’t as extensive as your spring to-do list, but you will need to do some housekeeping items before the cold weather settles in. Here is a checklist to help you complete your chores.

  • Move Your Air Stones: To keep oxygen bubbling in your pond through the freezing temperatures, move your air stones into an area that’s half the depth of the pond. For example, if your pond is two feet deep, position your air stones on a ledge or step that’s one foot deep.
  • Remove Glass: Drain, remove and store anything that has glass inside, such as your ultraviolet clarifier, pressurized filter and all-in-one filter. Keep them in a heated garage, basement or other indoor areas that won’t freeze.
  • Remove Ion Clarifiers: Ion clarifiers release copper, silver and zinc ions into the water to control string algae. Because copper levels are naturally higher in the winter, you can remove the ion clarifier and store it for the winter.
  • Pump Protection: Whether your pump feeds a waterfall, fountain or some other decorative feature, remove it and drain all the water from the tubing. Store your pump submerged in a bucket of water inside to keep the seals lubricated.
  • Nix the Netting: Before the first heavy snowfall of the season, remove your pond netting and store it until next spring.
  • Quick Pick Up: Clean up decomposing debris that can cause excessive toxic gas if your pond freezes over with helpful tools such as the Collapsible Skimmer and Fish Net or ClearVac™ pond vacuum. For smaller particles, rely on Seasonal Defense® which has beneficial bacteria with barley and is designed to work in cooler temperatures.
  • Switch Food: Help your fish transition to cooler temperatures by switching their diet to a wheat germ-based food like Pond Logic’s® Spring & Fall Fish Food. When temperatures reach below 40°F, stop feeding them entirely. Their metabolisms will slow down and they’ll hibernate for the winter
  • Get Your Plants in Shape: After the first frost, remove dead foliage from your aquatic plants. Trim hardy lilies and bog plants back and move them in the bottom of your pond to protect them from the cold temperatures. If you have tropical water lilies or other temperature-sensitive varieties, make room for them inside your home to regulate the required temperature.

Not too bad for a weekend’s worth of work! As soon as these chores are done, your pond will be ready for winter.

Pond Talk: What else do you do to prepare your pond for winter?

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