Dump techniques....

I have 2 trailers. The 17' is a pain to dump. Black and Gray are each 50Gal. Just plain slow, both tanks are slow especially the gray. I do similar to what many here do. Before I leave the campsite I pour a few buckets of water down the toilet, just to get it good and wet - you know make all the poop go with the flow when you open the valve. Also have a rinser on the black tank. Problem with the black tank is that the pipe connects to the right side of the tank (passenger side) and goes all the way across the trailer to the left at a slight downward angle - so not super fast. The gray is worse. The tank leans slightly forward and pipe is on left side dumping still leaves 5 - 10 gal of stinky gray water in the tank. If no one is waiting in line, after dumping the black tank drive the right side up a few inches on blocks and lift the front of the trailer as high as I can get it - wait 10 minutes as it dribbles out the last 5 gallons.

The 35' toy hauler on the other hand can dump both black and gray in 10 minutes or less. Each tank is 65Gal. Tanks are angled down towards the pipe, open the valve and it comes flying out - no issues.