I originally removed a 3" x 3" square section of the vinyl backing on my JBJ 30 to place the unit. It appears that users need to remove a larger section of the vinyl in order for the unit to function properly. I'm not sure why, but when I removed the rest of the vinyl up to the top of the tank the unit works fine. I've had it working for about a week now and all is well. Thanks for your help!