I'm not the person to be asking about wpsf numbers as all that tends to make my head spin but from the looks of your cab the 150 should be just fine in there. The goal you want is 50 watts per square foot (again I don't know how they get that calculation) but it looks like it would be more than enough. Is that the 150 you are planning on using? If so you might not even have to use a cooltube since that model light is not remote ballasted. Remote ballast means taking the ballast out of your grow area and locating it in a different place. The reason you do this is because the ballast is the part of your light that makes the majority of the heat. If you can move that outside of your intended grow area you will take your heat down at least 50%, maybe more, making a cooltube unneccessary. West if I were you I would go check out the Micro forum here on IC and see what some other people are doing, that was where I got introduced to this place and where I learned A LOT of what I know today. There's even a thread dedicated to 150 watt lights that's about 300 pages long so there has to be something you can use in there. Micro forum is located under Grower's Forums...