i used a power washer once, not a strong one though, and it worked great. made all the slime and algae come off. even the tough algae that i couldnt get off with a brush because all the tight fittings.
Wire brush to scrub off all I can, then I boil it for about 10 minutes. If I can't fit whole piece in pot, I will boil one section, then move it so another section is in the water. I figure, whatever I can't get with the brush, the boiling will take care of.