Please try the following test, especially if you have any ballasts, large pumps or x-10 devices near the osmolator. Test the osmolator in a seperate room from the aquarium, such as the kitchen. Use a bowl of water to dunk the sensor in to test it. This will rule out a product defect vs magnetic interference. If it still does not work I will get this replaced for you. If it does work you need to find the source of the electromagnetic interference and move the osmolator away from it.