I was thinking' about what you said yesterday, your box being too cold most of the times. I think that's good, because you will have less trouble with the hps now, both in reaching the needed temps and evacuating heat.
Small hint on how to get the exhaust working fine: You'll need to set the temp on the fan to about 24 or 25 C or whatever temp you want the room to be. Put the probe inside the room at canopy level and just set the fan speed to a minimum. It will start working in higher speeds as soon temperatures do exceed the temperature you've adjusted and slow back down as soon as the room is cooled down. If you see temperature rising above the adjusted value but the exhaust is not starting to run at full speed, turn it down to a lower temp so it will kick in earlier. I really hope it will work out for you man... when you told me you had +-20C temperatures differences over the day, I was getting a bit worried...
ps: still have the diy cool-hood in case it gets too hot in there. Best of luck captain! And good luck for the rest as well... shitty situation man... I feel for you bro.. :/
PS2: if you don't want the fan to change speeds every minute, crank the speed up a little higher, so it won't switch every minute...
