Custom shower. Short story is plumber did not make a pressure balancing loop when piping the body sprays. He made a simple loop. There are 3 jets on each of 2 walls. THe top jet flows full stream..the middle slighlty less..the bottom jets trickle. 3/4 inch valves and piping. Is there a way for me to fix this? Perhaps by regulating the flow out of the top body sprays to equalize pressure? Its all Grohe fixtures.