About Pond Water TemperatureA Division Of
Springtime Nursery

I found this  thermometer works best  for ponds, because  it has 4 foot probe which is stainless steel.  Nice thing about this probe is you can measure all the way down to 4 feet in depth.

It has a wireless monitor that clips to your belt

The best part of these thermometer is I can set it up and go inside the house and monitor the temperature of the water at night or any time for that mater  

Rounded Rectangular Callout: Here you can see  the cord going to  the soil of the pot  where the probe is inside  the soil of the pot 
Rounded Rectangular Callout: Here is the difference that 12 inches  almost equals 11°  
Rounded Rectangular Callout: Here is the monitor and it is telling me that the soil temperature is 73° 
Rounded Rectangular Callout: Here I am measuring
The surface water 
The probe is barely touching the water 
Horizontal Scroll: Farming water plants since 1988