Blagdon Force Hybrid 8000 Pond Pump

The problem with all these pumps theyonly give you vague ideas of their power capacity, it offers Max flow what on earth is that? I am pumping water up 7 metres it handles it alright although i would have preferred a higher output. They say ideal 1or 2 metres and ideally fairly flat but that doesn't produce a decent waterfall. It works well easily installed and cleanded with a karcher at the end of the season.