I recently placed and received a large order with MD. In it I bought a MJ 900 with the intention of using it in conjunction with the Phosban Reactor that I bought. I haven't opened the box or used the pump and have decided to get something smaller if possible. Can I send the pump back and exchange it for a smaller one? I think it has been under a month since I placed the order. Thanks in advance, I'm a very big fan of MD and have always enjoyed excellent service and prices! I will continue getting supplies from you guys as long as I'm in the hobby. Keep up the good work!