Is that 250hps air cooled? I'm also about to buy an HPS now that I know what I'm doing and do a comparison myself. I know my Mars has never yielded what my HPS did. Now my amare panels, those have given me plants the same weight as I was getting from hps.
But for cooling I actually had to shut down my tents this summer and ended up building a panda film room around my window AC unit so the unit is right in the room lol constantly working haha, but before I help I have to know a couple things, right now where do you vent the scrubbed air from your tent to, what season and temperature is it outside and what's the ambient room temps in the room your cabinet is in?