I would look into the new Tunze hub edition pumps. Two 6040's for the 50g would work or two 6075's. I have two 6040's on my 50g lagoon and they are awesome underrated pumps. Plus, they're Tunze, so they will last. In fact, mine are almost 10years old and still going strong. I can actually upgrade them both to the hub controller, as they make a retrofit hub controller for nanostreams with the blue 3 knob controller.
But if you're looking for MP style pumps, then I would just get some Jecod DMP's.
But if you're looking for MP style pumps, then I would just get some Jecod DMP's.