You need to purchase the Y splitter yes. I literally just went through this with two Klir-7's. I set the optical water level up on one of the two, and ran the cords for the motors to the 'Y'cable and then connected that to the controller. It works like a dream for me. So far I'm super happy with this configuration. You can order the adapter direct from coralvue as I did. It showed up promptly and at a reasonable price in my opinion.
