Ok, so here's my issue. We bought the boat a few months ago. It has a Purasan system on board with two Raritan Atlantes heads. Every time we flush we get a horrible sewage smell outside of the boat. Bad enough that we don't want to use them when our boating neighbors are here. At one point we had some sewage shooting out of the vents when we flushed. I ran some water down the vents thinking they may have been clogged. The smell still continues. I've pumped the tanks a few times still to no avail. It also appears to get worse when the holding tanks indicate half full. The remote indicator panel never goes below 1/4 tank when pumping out. This is not a vacuum system. For some reason I just can't figure this one out. Any and all suggestions would be greatly appreciated!!