I used a
Lifereef which uses a U-tube and it was 100% dependable, a lot of people swear by
CPR's they are cheaper but you have to hook them to a power head or an Aqualifter pump to ensure they restart in case of a power outage. Kind of an unnecessary risk in IMO, the Lifereef's aren't that much more expensive. (it's cheap flood insurance)
The bulkhead in your sump is great, it gives you the option of using an external pump, skimmer or refugium down the road.