I will be using a sumpreme classic mag drive pump 9.5 (950GPH) for my return pump. My overflow box uses a 1" bulkhead, so I am pretty sure it is rated for 600GPH. With that being said, will the mag drive 9.5 be too much? I plan on using a T connector on my return line to control the flow and I will have about 3 feet of head. My next question is, how big should the section of the sump with the return pump in it be? The pump measures 5"L x 3"W x 5.5"H I am assuming that the bigger the better, but I am using a 15 gallon sump so space is limited. Is there a minimum requirement?