If I may suggest before you settle on the Sewer Solution have a wee look at this video in another thread?
Comment on tank flushing :
From doing quite a bit of research it really looks like most of the “tank flushing options” on the market do not in fact flush the tanks unless they have a “straight line into the tank. The exception of course is the wand option and/or the tornado options
http://www.thorforums.com/forums/f4/thor-gray-black-water-valve-4451-2.html
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