Of all the mistakes I made designing and building this grow the worst one was with ventilation. I had the idea I would stagger the 3 lights every 8 hours. With LED's and or sealed rooms that would work. Here, with a shared air duct for the HID's, it didn't. I used the hollow wall ducting method with staggered, vertically, connecting ductwork.
Long story short it was a complete and utter failure! Light leaked from one chamber to the other and the connecting walls were about 110 degrees from floor to ceiling. It didn't take but a short time before all the light timers were running together. Taking out the walls in a living system took a full cycle but the walls are gone. I went from 3 scrubbers to 1, straight piped the lights and its running cheaper with better air flow.
jj