Here's what I use works great....flush little, drain, then flush little more and clean water!
http://www.walmart.com/ip/14504324?...39128792&wl4=&wl5=pla&wl6=78652195112&veh=sem
Wondered if those really worked. now we know! Thanks for sharing!
Just stick that thing down the toilet opening and let it run until you get clear water coming out of the dump hose. Use a clear dump hose adapter.
Randor-
Assuming the 4150 is the same configuration as the 4100/4200........ Nope, your 4150 does not have a black tank flush for the second black tank. This would be a great addition! I fill the rear toilet by hose until the gauge says full and then I dump #2 (no pun intended).
Hope this helps.
Jay