Now you’ve chosen what type of de-icer you plan to use it’s a good idea to know how to install them. It is best to place the de-icer in your pond at the time of winterizing your pond. You may not necessarily have to have it plugged in but it is staged and ready to go. The floating de-icer is best installed away from the edge of the pond as far towards the middle of pond as the cord will allow, if you have a larger pond you will want ot consider using multiple units. Many floating pond de-icers come with attachments to keep the heating element from coming in contact with pond edging or equipment.
The submerged aquatic de-icer is best placed at about the mid-depth range of the pond. Placing it too high can create problems and possible leaks if the winter weather gets too severe, and/or a very splashy display; and placing it too low will circulate the bottom water of the pond to the top which can cause the pond to get too cold and stress or weaken the fish in your pond, it also makes it a bit more difficult to get to if you need to service the pump.
The aerator de-icer should be installed with the air diffusers also at about mid depth in the pond. Pond aerators can be purchased with multiple outputs, if your model is equipped this way I suggest utilizing multiple points of aeration in the pond. The airlines leading to the diffusers will most likely freeze into the ice in very cold conditions and typically will not represent a problem.
If you are installing your de-icer AFTER the ice has come take some precautions when working around the iced over pond. DO NOT TRY TO STEP ON YOUR POND TO GET A UNIT OUT TOWARDS CENTER, at this point you need to settle for close to shore for all installations. Do not try to break or chop a hole in the ice, not only is ice of only 2” thick VERY difficult to break open, but the noise created by the chopping, pounding, and cutting is very stressful to your koi and pond fish who are now in a deep winter stupor. The term stupor is used to describe the state of being in which pond fish basically shut down, are extremely quiet, and do not move. The sudden noises will take them out of stupor into panic which is not a good transition for any fish to make during deep winter giving your pond fish and koi great stress and possible death.
Best approach is to use hot water and slowly melt a hole into the ice until it is open enough to install which ever type of pond de-icer you intend to use. The hot water approach is very effective, and very quiet. Keep an eye pond your pond during the cold spells and snaps and react accordingly. Good luck.