I'm currently making a 10 gallon sump for a 20 gallon display tank, but I'm not sure what exactly I should choose for a return pump and overflow box. My tank is not drilled so I will need to use a hob. I'm confused as to whether I'm supposed to get an overflow that has a faster gph than the return pump or vice versa. It seems to me that with a faster return pump, the water level of the sump will be low since it's pumping out more water than the overflow can pump in. I also don't know what brand to choose from. Edit: I managed to get some help from the LFS and now have what I need.