Don't quote me , but I think you have to have the Dump Valve under neath the trailer open when using the black tank flush . It rinses the walls ,but isn't supposed to be used for filling the tank.
It was a rainy few days at Algonquin Prov park...tarps kept us dry.
Wayne --Belle River (Windsor), Ontario
2013 Sunset Trail Reserve 25RB..(just sold it)
2015 White Chev Silverado 2500HD 4x4 (6.0 l gasser)
2003 Mountain Star 890SBRX Truck Camper