water movement in tank questions

[Sea Witch]

Hi there: My first question!

I'm not sure if it should be in the DIY section....Can someone explain to me about spray bars? Are they typically spraying onto the surface of the water or underneath?

If it's underneath, isn't that a laminar flow (to be avoided)? Or is there such a thing as a spray bar that moves?

And where do you find spray bar type plumbing fixtures?

thanks all,