Knowing the water temperature of your pond can help prolong the plant and fish life of your water garden. If your pond is near the point of freezing over, you should either use a deicer from pondplanet.com or pour hot water over the ice to make a small hole in the ice. This will allow harmful gases to escape which will also save your water plants and fish. Under no circumstances should a pond owner rely on guess work when it comes to determining water temperature. Our Pond Thermometers are extremely accurate and long lasting. They are a smart investment for any pond owner who wishes to prolong plant and fish life.