The Big Blue Wheel Type Thermometer for testing the temperature of your pond, as did you know that you pond water temperature effects your pond fish health.

In spring- the fluctuation in temperatures can be very stressful on your fish. (those who have wintered in your pond especially!) Two ways to help with the stress. 

When your going to have a cold snap, turn your fountain or waterfalls off to slow down how fast your pond water cools.


Add pond salt to help develop a healthy slime coat  on your fish. This helps the fish naturally fend off any bacterial infections and parasites.
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Summer- The perfect pond water should be in the range of 68  to 74 degrees Fahrenheit. Water loses much of its ability to hold oxygen when the temperature is above 85 degrees.
Your fish won’t be able to breathe. This is when aerators, fountains and waterfalls help oxygenate the water. (Higher oxygen levels also decreases algae growth!!)

Winter- Your fish’s metabolism slows when your water cools down. They don’t need to eat when the temperature stays below 39 degrees Fahrenheit. An easy to digest food is 
suggested if the water is above 39 degrees. If you live in an area the your water freezes, keep part of your pond open so that the toxic gases can be released. Don’t break 
the ice to keep an open hole, the shock waves through the water can hurt your fish.

Its always a good Idea to have some sort of thermometer in your pond.