Have a 6'x6' tent with a 600 watt digital MH/HPS switchable ballast that I plan on picking up from HTG....what type of reflector should I get,going air cooled? Bigger the better? 18''x15'' or bigger/smaller? They are rectangle with the glass. Running SCROG big as possible. Thanks...a cool tube is another option..thought that the rectangle type would give more lumens to the canopy though. Let me know! Plan using the 6 inch vortex to cool and clean through scrubber.