Well, most folks'll tell ya they like ~5,000 lumens/sq ft for best results with HPS. A 1000W. covering 48 sq ft gives about 3,000, which will certainly work. You could start there and add to it if necessary, as long as your electrical supply and ventilation allow for such expansion.

The switchable ballast idea makes sense. Filtering incoming air has worked well for some folks on this board. You might check with the local Cooperative Extension Service and see what's in the local air that you would need to filter out.

Scrubbers? Can Fans are great. An 8" fan driving a Can 66 filter might cut it. May wanna go bigger; but those filters are conservatively rated and last way longer than the year I hear folks talking about.

[attachment=o227967]

That's a 6" 464 HO sucking through a ceiling-mounted Can 33 and firing directly through a wall. No ducting--a straight shot. :thumbsup: Tight fit, though.