I have two fairly large fans above my tank that take care of most of the work, they also help increase evaporation so I can add more kalk

If the two fans cant keep up I have a chiller as well.
It's amazing what fans will do... I'm running 2-250watt HQI ballasts, a 400MH magnetic ballast and 2-110watt Actinic VHO's on a standard AG 120...