Ok well I want to start my first post off by saying how much I've enjoyed this site. I would have never even known where to start if it wasn't for you guys. This is my first post...and I'm dedicating it to my first grow. My first questions involve the cabinet. It's going to be somewhat stealth with dimensions of 50"H x 48 "W x 20"D. I'm running a switchable 400 watter and have both the MH and HPS bulbs already. These are running under a Hydrofarm Air-Cooled hood with a 6" flange that will be down-converted to the 4" inlet on a 465 CFM centrifugal blower. I know the blower is probably WAY bigger than what I need, but will I see any problems with using a fan this big? Even though it's hooked directly to the hood, will it still pull enough air from the rest of the box to ensure adequate ventilation? Just for fun, what kind of yields should I expect once I get a little better at this? I'm also wondering about the intake. I got the idea to go with (2) 2"x10" intake grills (like the kind you see on ceilings or floors for the AC). I was thinking about running a simple filter on each to prevent dust, bugs, etc. from coming in the intake. Are two 2"x10" inlets enough? Will the filters restrict flow too much? I decided on these grills because I need something relatively low-profile so I can push it up close to the wall. When I was buying some of the equipment, the guy at the hydro store acted like PH and TDS in soil grows wasn't all that big of a deal. He acted like PH and TDS wouldn't fluctuate enough to even worry about it. Is he full of it? I went ahead and bought a nice little PH meter, but should I pick up a TDS meter as well? I'm sure I'll have more questions as the grow comes along, and I appreciate any help you guys can give.