Blow out or suck in?

I just had a wierd thought. I have a water cooled system with 2 fans on the radiator (push & pull). I recently made a 92mm blowhole ontop of my case and i was wondering...
If im using water cooling and all the hot air from the cpu is going out where the radiator is, should i make the 92mm fan still blow air out of my system or should i flip the fan over and make it blow old air in.

You're water cooling man. Why do you want all those fans? I highly doubt you need them