I've been doing a little research into trying to add a sump to my fluval flex. I'm looking at the fiji 12 as it would fit just right under my stand. I was looking at the CS50 HOB overflow as a way to get the water down to the sump as it's not drilled and I feel like getting it drilled would be far too much of a hassle while it's still up. I'm curious if anyone is familiar with that overflow or might have some other recommendations. I'm keeping the stock lid for the flex so I only have just over 6 inches of width to put the overflow box. Also the overflow box states it is up to 300gph but my pump is the sicce syncra silent 1.5 at 357gph, so would that be too much flow for that overflow? Thanks for any advice!