I use a 1/2" rigid copper pipe, actually 9/16" diameter hooked up to a 1/3rd HP sump pump. It has enough water flow and pressure to lift a 6 gal. Better Bottle off the pipe if I don't hold it down. The Oxiclean drains out at first, but when the foam builds up it quits draining. I have never had it not become clean by that time so I don't worry about it.
It also cleans corny kegs before the foam starts to overflow.