Welcome aboard Shake.

Before going shopping yesterday, I re-read Rhizome's guide to setting up a grow room. I was concerned that my "auto air cleaner" idea might not let enough air in.

Since our "room" is more like a grow room within a grow room I decided it would be best to treat the issue as a passive intake. Although I have no idea how much CFM the 5 inch exhaust from the A/C is flowing I figured that the 5 to 6 inch neck of the auto air cleaner could be too restrictive.

I ended up getting two 12 x 14 ventilation grills. We'll cut out an 11 x 13 hole through the wall and mount a grill on each side. I also picked up a "cut to size" washable air filter. It's enough to make a filter to back each grill. This vent will open into our shop and we're hoping that light leaking out won't be too much of an issue. If it is, we'll come up with something to deal with it.

Kudos to Killa, again. His tip on more frequent calibration of our PH pen was right on. A large bottle of calibration fluid showed up a couple days ago. We hadn't calibrated our pen since we bought it for our last grow. WOW! It was off on the high side by 1.7. We'll be checking it every week from now on. Not being accurate explains some of the issues we had with our last grow.