Not sure about a top off unit yet Snake. I'm sure eventually I will add one though. Also I am drilling the sump for a 1" bulkhead that will supply the return pump and I'm not sure if the Pan World pump can draw suction to all me to put the return chamber in the center of the sump, and my stand won't accomidate running 1" pipe behined the sump, there just isn't enough room.
Duane glad the diagram could help.
Vince.