It's normally the other way round, Pump to CPU_FAN at 100% in the bios, Fans connect to any other available 3/4 pin fan header with the included fan splitter.
It is classed as a CPU optional fan header. So yes you can use it, just be sure that the pump is set via which ever header it's on at 100% in the bios, better still you could always go 3 pin to molex for a better 12v feed.