I like Mike's a little more, but this is the set up I had when I cleaned (before having access to Les's wisdom), in fact the pump still ran fine the day i removed it, if someone needs a pump cheap ready to go, just PM me.
As you can see, I had the starve set with a ball valve barely closed, and the regulator bypass came in close to the pump head, and the dwyer fed in between....foolproof, always worked.
I can think of another reason to Stay with a simple siphon, you don't have to worry about blowing diaphrams and bypassing your chem system just because you are running high pressure, 800 psi is brutal on diaphram pumps.
And O2 rinse cleans HXers not scales them.