Outdoor To Indoor/Outdoor Garage Build 9*20*6

Welcome my fellow GC members. I'm attempting my first Outdoor garage grow. I had to move indoors again because some fools ripped my 20plant outdoor grow this season and, like the rest of you guys, I HAVE TO HAVE MY HERB! So the theme of this grow will be: CAN'T STOP A PLAYER! This isn't my first rodeo. I have one previous indoor grow and two seasons outdoors. I have picked up a lot of knowledge from Old P, Dank in the outdoor section. Also, I've gained some knowledge of living organics from Lumper and the rest of the gang in the organic section. I'm ready to get this party started.

Now some info on my space. It's an unattched outdoor garage. The dimensions are 9*20*6. I know that it's a lot of space and I'm aware of all the potential problems that I will encounter in this space such as air flow, temps and humidity issues. But I'm a firm believer that any problem can be over came with either ingenuity or straight cash. And since I'm all out of cash then I guess I'll have to use my noggin'. My plans are to split thw room into seperate chambers for flowering and veg after this run when I have more cash on hand.
The equipment that I have are 4 400w hps with mh conversion bulbs and one 600w HPS. On this run, I'll just be running the 600w HPS during veg and flower. Right now I have only a 20amp breaker on this circuit, therefore I can only run one 600w. This is because in anticipating of temps dropping during winter months I'll have to add a standup oscillating heater and they rate out at 1200w on 12.5 amps. I'll be adding a 6in inline/carbon filter combo as well right before flower. The plan is to use a passive intake system. My only problem is that the walls in my space are straight cinder blocks and the roof is plywood. I caught hell drilling holes into the wall with mason bits just to secure and blackout the windows. My only option, besides running pipe under the wall, is to have my passive intakes in the ceiling. I know that this is not ideal but it seems to be the most practical solution. My question to the experts is, since my walls are cinder blocks then insulation shouldn't be necessary correct? I know that maintaing temps with intake from outside will be problematic but it's all I've got.

I'll be running 10 Dinafem Power Kush, 1 Blue Mystic and 1 Ice from Royal Seeds (freebies from Attitude). Seeds are being germed as I type. I'll be running 5gal pots in organic soil. Ferts will Be General Hydroponics Organic line. I'll also be supplementing with Aerated teas. It's too late to turn back. Here I go. All help and advice will be greatly appreciated but please keep it respectful and act like adults. I'll pust pics as I go.