Fish Habitat: Does Aeration Heat Up the Pond?

Optimize your fish’s chances of survival during heat waves.

We often hear that aeration will heat up the pond on hot summer days. The warming up of the water will eventually make trout stop feeding and can eventually kill them. Sometimes oxygen is not the only limiting factor.  Maintaining cool temperature is as important for trout species. Find out more about temperature requirements for fish species here.

Contrary to what many believe, it is not the warm air coming from the compressor that warms up the water; it’s the sun heating the water that is circulated to the surface, making the entire body of water warmer. On hot days, with a bottom aeration system operating, the cool waters are brought to the surface where the heat increases water temperature. As the circulation continues warmer waters replace cooler waters at the bottom of the pond.


Use of a Thermostat to Control Your Aeration System

The C-10 thermostat switch allows you to aerate your pond without heating it up

If trout or other species of temperature sensitive fish are present, this warming of the pond can be unwanted. How can you prevent this warming effect, yet keep oxygen levels high at all times? The best way is to operate your aerator only when the outdoor air temperature is below a certain temperature to minimise heat transfer from the warm air.

Here is a guideline for the main species of Trout

  • Speckled trout: Run aeration when the temperature stays below 19 °C or 66 °F.
  • Rainbow Trout: Start aeration when the temperature drops below 22 °C or 72 °F.

These thermostats are Plug-and-Play and require no additional wiring.  They are also recommended for de-icers in winter.

This thermostat is designed to save you money on your electricity bill and ensure your water is kept at the lowest temperature at all times. Your current aerator plugs directly into the unit which controls when your aerator turns on based on ambient air temperature.

Set your thermostat to cooling control on your pond aerator and when the temperature will exceed a predetermined temperature, the aerator will stop which will actively stop the circulation of water, keeping the cool temperature at the bottom.

Night time is normally cooler; as soon as the heat threshold is crossed, the aerator will resume the important effect of circulation in the pond water cooling it off and raising its oxygen content.

Ideal temperatures for fishes

In typical situations, when using the thermostat control unit, your aerator will turn-on in the evenings and on cooler days only, thus allowing natural temperatures to be established at the pond bottom.

This unit comes with an 8′ power cord, simply plug the thermostat into a standard 110/120 volt outlet. Then plug your aerator into the outlet of the plug of the thermostat.

Temperature range is -1.1 °C (30 °F) up to 43 °C (110°F) (differential of 1 °C or 3 °F). This device is for appliances operating at a maximum of 16amp/120v.

Benefits of Pond Aeration

  • Increases dissolved oxygen and limits thermal stratification
  • Stops oxygen-related fish kills
  • Reduces nutrient levels associated with algae growth
  • Improves fishery production by expanding oxygenated habitat
  • Reduces mosquito insect hatches (West Nile virus)
  • Eliminates foul odours from undesirable dissolved gases
  • Pre-wired thermostat control


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