Black Holding Tank slow to drain...
Our Black Holding Tank is slow to drain. Can this be caused by a bad Air Admittance Valve or a clogged vent cap or both? The tank dumps fine at first, but it eventually backs up and then very slowly...
Forum Discussion
Sounds to me like you may have the disk they cut out to install the drain line still in the tank. As everything moves towards the drain it brings the disk with it until it gets to the tight spot then it jams up.
