Hmmmmm.....back to the drawing board. But, I am with ya one the passive exhaust thru carbon. What I was thinking is if I had those T's in that 4" PVC, and those T's all had a floor grate, I could suck that air in from the outside, floor level, and it would naturally exit the T's inside the growroom and keep well ventilated. I had planned to exhust the air from the top already. I am trying to design a kick ass room, and I have to watch I dont assemble a wall or whatever and then I cant get everything where I want it. Floor is built, as is both side walls, just not put together yet. Plus I am putting my outlets directly in my room wired to their own 30 Amp breaker for each one. So before I do anything, I need to always be looking ahead a few steps. I want to build it ONCE......lol I already have 2 Sun Gro II 1000 watt HPS/MH lights, so ventilation and fresh air is a concern even though they will have their own fans sucking the heat out as well. Hmmm, I even wonder if those 4" fantec fans would fit PVC. If not I could crosscut both ways and jam in there, band clamp it, and duct tape if needed.

I covered the walls with blueboard and will ty-vacked them when I assemble all the walls. Sounds neurotic, but I want to keep noise down, and atmosphere as close as needed without making 97 changes daily. So, I figured best to seal it off as good as possible, and go for airtight. I can put in and take out what air is needed versus hoping some gets in from the outside and some escapes to keep temps down.

b0nger