Thermometers for Ponds
A pond is a living ecosystem and therefore is dependent on the waters temperature. If you have fish in your pond, they a completely dependent on temperature, as their immune system is very sensitive to changes in temperature. It is important to check the temperature of your pond on daily if not bi-daily schedule.
The two most important times to be checking your temperature is in the late fall and spring. Fish will go dormant once the temperature reaches below 50 degrees Fahrenheit, so do not be shocked if they are not eating or appear sluggish. At this point you need to stop feeding your fish, and stop running any bacterial treatments through your system. It is best to run your last treatment, to make sure the fish are clean and set for the winter when the water is between 55-60 degrees Fahrenheit.
When Spring returns, you must wait again for that 50 degree Fahrenheit mark. At this point begin to feed your fish again, and treat them for any physical issues they may develop. This is not something to be alarmed about, because the fish was dormant over the winter, and it may take some time for their immune systems to wake back up.
You should invest in a good pond or pool thermometer that comes in an enclosed plastic case keeping it from freezing and cracking. You can look for a floating /sinking thermometer, this way you can tell the difference in temperatures from the bottom and the top layers of water.
When purchasing a thermometer, you will want to check for range in temperatures it measures. You will also want to see if it measures in Fahrenheit or Celsius, or both. This way you are measuring with the system you are used to.
A thermometer can be left in you pond, just be sure to attach it to a thin rope so you can reel it in. It may be a good idea to keep track of the daily temperature of your pond in a notebook, so you can become used to what the temperature should be at. You can keep track of other important details as well in notebook so you remember what tasks need done when, or how to best do them!.