steve@freshwater is right in what he says about aquatec pumps - we supply them as standard pumps (delivery) for some of our systems, some ask for shurflo/flojet but have supplied quite a number of aquatec pumps and actually run 2 of them ourselves - very very good pump, have not had one come back yet, at all.
the 8800 model was designed for the merlin and really does the job well, well worth the money.
Paul mate, I know you have forked out a bit lately for your kit but the one best piece of advice I can give you is this - always go for MORE than you need, you may need it someday.