[Warning: Not for the squeamish. Though you may get a chuckle]
I have a vacuflush system on my Pilot 34. I added a new tank gauge last year and due to replacing batteries, had to recalibrate it at Empty and Full. Soooo... it was probably about 3/4 full of waste and I figured I'd just pour a bucket or two of fresh water down the head until it seemed full. As I was pouring, the vacuum pump kept running and running. I turned it off at the panel, went and looked in the engine room and saw that the holding tank had ballooned (like a portable gas can sitting in the sun). CAPTAIN! SHE'S GONNA BLOW! We quickly cast our lines and headed over to the pump out station. I carefully unscrewed the deck cap ever so slightly and it started to hiss. When it seemed to be done, I unscrewed the cap a bit more. BOOM! Let's just say it was a real sh*t show.
So... now what? The tank and hoses look ok, with no signs of leakage. The mere fact that it held a bunch of pressure I take as a good sign. But now I'm thinking about the vent line. How come the excess pressure didn't bleed out? I have an in-line filter on it. Guessing that is now clogged? Maybe that is all? I don't fully understand how the vacuflush system works. What should I do to make sure all is good?