When I rebuilt my own plumbing and waste tank system last year, it was not pleasant, but a few of the ideas above with regard to flushing the system worked well. I removed 35 ft. of hose, three Y valves, and more than 20 hose clamps that only complicated a simple system. I can't imagine why it was plumbed this way, but you never know about previous owners and their habits. If you already have the system you want, then just replace whatever you have, but make all the decisions about adding or subtracting things before you complete the job. If you've got to get down and dirty, do it all in one unsavory moment. The only thing better than leaving the Admiral home would be getting her to do the job instead of you.