Hi! I've got a 29G reef that has been running for 6 months already, and I am planning on adding a sump and a refugium. The problem is, my aquarium does not have any built-in overflow box. Does anyone have any solution to my problem? I have also read about H.O.B. overflow boxes by CPR Aquatics. However, there have been negative remarks that these H.O.B. units can lead to overflowing of the tank. Is it true?