what ventilation system should i be looking for?

Hello there Bruiser. I myself am a closet grower and just like you I struggled with overheating and ventilation problems when I first began growing in a smaller space. I know some of the other guys have given you some pointers and I would like to suggest this to you. I myself use an item called an Squirrel Cage Blower which is highly effective at removing heat. These blowers are basically like high powered bathroom exhaust fans. I have done my best to calculate the cubic feet of your room with the information you provided. It is 460 Cubic Square Feet large. I suggest you go to this website http://www.mdhydro.com/squirrel-cage-fans.html and consider buying the 465cfm model(CFM=Cubic Feet Per Minute). They are very easy to setup and the website I directed you too is very affordable and very possibly the cheapest place on the net. I buy almost all my equipment from these guys and I trust them 100 percent. I'm almost positive that this will eiminate your heat problems. Now I'm not sure if you know about rates of air exchange but it is advised that you cycle all the air out of your room at least once per minute or five time a minute for optimum results. If you don't know how to calculate that what you do is take the cubic square feet of your room and purchase a cage fan that meets your CSF(cubic square feet) or exceeds it. With your 460 CSF grow area you would need the 465cfm model to exchange air once per minute with five cfm's left over. In order to exchange the air in your room five times a minute you will need a exhaust fan capable of 2300cfm's a minute which is damn near impossible to find so I would suggest going with their 800cfm model if you want to push more air out of the room faster. I hope I could help and good luck to you. ;)

I forgot to mention to you that exchanging the air five times a minute is not totally needed to grow cannabis. Removing all the air out of your room once a minute will remove all the hot stale air from your room well once a minute. The reason growers like to move air five time a minute has nothing to do with heat but has to do with making sure your plants are getting enough fresh air to convert sunlight into energy for maximum growth potential. Peace.

Well thanks alot zandor,harddon :) ZERO Revolt.,all your information has been more then helpfull! :) ,thanks for taking the time and helping out a fellow grow buddie,also Zandor could you post the pic of your 1000w light 12" away from the plants,I would love to see it!,also do you have the AC close to the lights? anyhow show me a picture would ya dude!.......much appreciated..

I was wrong on the estimate, it's 13 1/2" from the average top of the canopy.

Yes that is a temperature probe, the temperature is 68 lights off and as high as 74 with the light on. No cool tube, no hood no venting, no exhaust just one 1000w Hortilux bulb start to finish.

My camera does not like taking pictures of 100w bulbs.

The place where i work has a shop floor - ( where i work ) and Offices. All the dickheads in the office were complaining recently about how hot it was in the office ( even though it`s far hotter where we work and no-one gives a shit)!!
Anyway - they went out and bought a small portable air-conditioning unit and i was quite stunned at how amazing these things are !! You walk from the shop floor into the office now and it`s like walking from the sahara to the North pole in a split second!! -- i thought `` GROW ROOM ``` straight away.
All they do is suck air in from outside and chill it but fuck me they drop the temp of a room hugely!!!
u`d have to have a 4" (120 mm) hole in ur wall for intake and i don`t think they come cheap but by the sounds of it ------ if u`ve got a grow room that size then ur obviously not just growing on a small scale and it would be an investment.
i`m planning to have a room of similar size soon just for growing and if my budget can stretch then i`d certainly consider 1. depends on the scale of ur grow though really.
I know all about the problems of heat -- killed a few babies from heat recently so been looking into all aspects of controlling temps.
Hope this isn`t just a waste of ur time ---- just my thoughts in type!!

lol Zandor, I see you talk so much about your plants and I have been tyring to find a picture of your grow room and plants. I finally see 2 of your plants and PART of your grow room, you're one amazing grower man. You should be nicked dr. greenthumb

Joel this is a typical KBS grow and I have grown KBS for several years now.
I have taken down my KBS room thinking we were selling our house and moving but my wife put that off for another year and there is no point in rebuilding it for only a few rounds. There are so many other way's to grow I'm just playing this year, working on book's and other projects. KBS is a full time job and requires a lot of time and money to run.

The second picture is not mine it's a friend's. I taught him how to grow trees. I guess he was a good student that plant yielded just over 3.5 pounds dry and one of the largest harvests I have seen in many years.