I have a 11,000 gallon pool with a Mineral Springs SWG. Its 5 years old. I have read that the cell lasts 3-5 years. When the cell fails, is it a gradual thing or does it happen all at once? Do you get a fault or warning message on the display? Also is there any way to test the cell to make sure that the cell is definately the problem? And finally! where is the best place to buy a replacemenmt cell. Thanks for the help!