I've used this device for the last year. It is a great asset to any RV'er. For a year, I tried to get old toilet paper off the sensor probes on in my black tank. I tried "tissue eaters", ice cubes, and multi multi emptying with no luck. I bought and installed the Tornado. The next tank emptying and a thorough use of the Tornado and my sensors started working flawlessly. I would recommend this device to all RV'ers. It really works!