No need for a sparge arm and it would actually get in your way the way I batch sparge. I just dump the sparge water on top, stir the hell out of the grains to mix the water and extract the sugars, vorlauf to set the grainbed, drain, repeat if necessary.
Cellar Door Brewery
Primary: Smoked Porter
Secondary: Flanders Red 2010
Kegged: 10.10.10, Robust Porter, American IPA
"Without algae, there would be no life on earth, the seas would be sterile and the land would be uncolonized."
-Sir David Attenborough