[SkiFletch]

Centrifugal pumps like the barracuda have one big downside, they cannot create much negative pressure suction on the inlet side of the pump. This means that if the pump is forced to create a significant negative pressure (even a few inches worth of water) the output pressure and therefore flowrate will be significantly lower. The specific model of centrifugal pump matters not, fluid dynamics hampers the design of any/all centrifugal pumps this way.

For example, a Barracuda may be able to generate 18' (432") of positive pressure; if memory serves they can only generate around 1' (12") of negative pressure before they cavitate (produce bubbles), and 4' (24") of negative pressure before they shutoff. I might be mistaken on those values, but the idea is simple, you can have very little negative head on these pumps before they start encountering significant operating problems.

This means the pump cannot be situated significantly above the water level of the tank upon which they're drawing from. Furthermore, they need large inlet pipes to draw off of. A Barracuda works best if it can draw directly off a 2" bulkhead fiting in the side of the sump tank. If that's not possible, at least use a 1.5" and prefferably a straight, short run. Trying to supply it on another tank with an overflow box is an exceptionally bad idea. These things suck a LOT of water, more than most overflow boxes can supply.

Unfortunately you allready have a lot of water in the sump which makes drilling the bottom side of it for a bulkhead (ideal) very difficult. Perhaps consider dropping a big magdrive in the bucket and pumping water temporarily into the display tank while you drill the sump tank and install the bulkhead/pump. Your only other real options for this would be to suspend the pump just above the water level (which could be disastrous if it ever falls in), or to use 2" spa flex, start a siphon, and pray the siphon never breaks (again not something I'd be comfortable with)