[hgs_notes]

The ball valve may work, but I think it will probably feel like full on at about 1/3 open. Depends on the amount of total flow you have. Part way open on that valve may be enough to allow all the flow the system puts out. A small orifice (washer) in the valve inlet might help control it better. Another option is a smaller ball valve. You'll just have to try it out and see what you get for results.