So that means if I place this pump in the bottom of the bucket facing up, and place my hand at the surface, I should feel it?
I would say there's definitely something not right here... I use a Mini-Jet 404, which produces about 1/3 less flow than the Maxi-Jet 600, to mix sw in a 5g bucket at work. I mix up 4g of sw at a time, as I don't need more than that for the tank in my office, and the Mini-Jet 404 "boils" the top of the water.