Pond Winterization: Heaters vs. Aeration

Published on August 27, 2023

If your pond becomes covered with ice, there is no way for the gases to escape or for fresh air to reach the water. Oxygen levels decline, and toxic gases build up in a potentially deadly combination for fish and plants. Bottom-diffused aeration and de-icers help maintain an opening in the ice to increase water movement and oxygen saturation.

Heaters vs. Aeration for Winterization

There are multiple factors that must be considered when designing any pond. When planning a pond in a cold weather climate, the proper care of fish during the winter months should play a vital role in the design of a pond. Beyond typical design features like shape and depth, a decision must be made as to how to handle any ice that forms on the surface of the pond. When left unchecked, ice can completely cover the surface of the pond, allowing toxic gases to accumulate in the water. This could eventually lead to fish illness and even death.

There are two common approaches to pond winterization and dealing with ice when there are fish in the pond — installing a pond heater and installing an aeration system. While either system can help fish survive through the winter, aeration offers distinct advantages over heaters that should make it the choice for every pond and every client.

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What’s the Difference?

Pond heaters are systems designed to float at the surface of a pond and keep a hole in the ice throughout the winter. This small hole is intended to allow gas exchange in the pond. Toxic gases that can build up under the ice are able to vent out of the pond.

This venting will lessen the chances of a fish kill over the winter months. Pond heaters come in a variety of sizes and should be selected according to the pond size and the climate. These are intended to keep a small section of a pond clear of ice — not to heat the entire pond.

In contrast, aeration systems are designed to circulate the water body by placing diffusers at the bottom of the pond. An external compressor allows air to pass through the diffusers, lifting the water and adding oxygen to the water body.

Aeration systems will not keep a pond clear of ice, but when properly installed, they will keep a hole open in the surface of the ice. Thus they allow for gas exchange and prevent gases from building up in the water body. They will also maintain a higher oxygen level in the pond, further contributing to fish health and well-being throughout the winter.

How Do I Choose?

Combining a pond de-icer and aeration unit will ensure that a hole is kept open in the ice, water circulates properly, and dissolved oxygen levels remain high.

The primary factors that should be considered when selecting a system for your pond are the costs associated with the system, the health and well-being of the fish and the additional benefits to the pond system.

Pond heaters offer a relatively simple and usually inexpensive design but can be very costly to operate. They do not provide much additional benefit to the pond beyond maintaining a hole in the ice. A standard-size pond heater is 1250 watts. Smaller and larger units are available, but to properly keep a hole open in an average size pond, a 1250-watt heater is commonly recommended. The operating cost of a 1250-watt heater can easily run over $100 a month in the colder months when operating 24 hours a day. Even though the units are relatively inexpensive, they can become very cost prohibitive to run for an entire winter.

This is in stark contrast when compared to aeration systems. Aeration systems will have a similar initial purchase price but significantly lower operating costs. Aeration systems designed for some of the largest water gardens will only have operating costs of $2 to $3 per month. This simple fact alone makes aeration a much smarter choice for any pond build; however, in addition, aeration also offers other benefits above and beyond what is offered by a pond heater.

Benefits Beyond Pond Winterization

Water garden aeration systems can be utilized for more than keeping a hole open in the ice in the winter. It is highly recommended to keep an aeration system installed and operating throughout the year, as it will offer benefits to the fish and the overall pond ecosystem. Aeration systems increase the oxygen levels in a pond while circulating the entire water body. They offer much more aeration than a simple pump and waterfall circulation system.

Creating an oxygen-rich environment will lead to better overall fish health and help strengthen a fish’s immune system, allowing the fish to better fight off diseases that can come from an improperly maintained ecosystem. The higher oxygen levels will also lead to increased beneficial bacteria growth in the pond and help the overall effectiveness of any bacteria treatments being added to a pond. The increase in the effectiveness of beneficial bacteria will lead to reduced nutrient levels in the pond which will help limit algae growth.

There are multiple factors that must be considered when designing any pond. Winterization can play a vital role in the health of the fish and the overall well-being of the pond. While pond heaters may be inexpensive to purchase and easy to install, their operating costs far exceed the operating cost of a pond aeration system. They also offer no additional benefit to a pond beyond maintaining a hole in the ice. Aeration systems will not only keep a hole open in the ice in the winter, but they will increase the oxygen level of the pond and provide year-round benefits, creating healthier fish and a better pond ecosystem.

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2 thoughts on “Pond Winterization: Heaters vs. Aeration”

  1. Great article! Very informative! Harrison is so knowledgeable and really knows what he is talking about.

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