400w learning curve.

I flowered my first batch a few months back I used a 150 watt LED array with two additional 30 watt LED "flood lights" I had great beginner's luck no real problems good yield good results. With my new confidence I decided go ahead and buy a 400w HPS light with a 4 x 2 x 5 grow tent. Digital ballast Cool Tube. My tent is in my spare bedroom and the ventilation vents directly into the room, I know this is not ideal but for discretion it's necessary. I've been having lots of problems with high temperatures and low humidity and have been trying to figure out how to get this set up running smooth. I harvested two plants from the overheated room and let's say I just didn't have the same luck I did with the LEDs. I have the temperature currently under control because I've dimmed the light back to 50%being as there's only one plant left in there and I seem to have the temperature under control for now. I have a new crop waiting to go in a few weeks and I want to crank the ballast back up to 100%. I purchased a small swamp cooler to try and lower the temperature and also increase my humidity, has anybody had any experience with this? Do you think this will be enough or will I have to take more drastic (expensive) measures?

What are you using for ventilation? I would suggest some type of carbon scrubber and fan that will pull at least 100 cfm, through the cool tube and out of the tent. That would turn the air in the tent about every 20 seconds. At those flow rates, you don't really have to worry about heat inside the tent, because it will be within about 2 degrees of the room temp. Since you are not getting a temp rise inside the tent, it will also maintain virtually the same humidity as the room. Now you only have to worry about maintaining the temp/humidity in the room.

Edit: As far as the swamp cooler, are you going to be recirculating the air in the room or are you going to be bringing in fresh air? If you don't bring fresh air into the swamp cooler, you are basically using the swamp cooler as a humidifier, and yes it will raise humidity but do minimal cooling. When bringing fresh air in through a swamp cooler, depending on the dew point outside, swamp coolers can be very efficient and will also raise the humidity.