I found a great way to clean the RFF - you get a wet arm though
Put your outlet tap half way up the barrel. Attach a flexible hose on the inside of the barrel that can reach all of the bottom section. turn tap on and move hose around to clear solids via siphoning.
The reason its half way up is so you can reach the pipe and so its below water line to create siphon.
We tried this method with 32mm outlet and 19mm pipe on the inside - works a treat and only lost about half a bucket of water and crud.
Jay
P.S. Diagrams or pics can be provided if necessary
