DR100 400w or 600w ?

Hey guys I have a DR100 and dont know how big of lights to get. The tent is 39.6"x39.6"x72" can ya plese help a fellow grower out ?

check this out http://cheaphydroponics.com/Merchant2/wattcalc.htm

go as big as you want. if you don't have the proper ventilation you won't be able to control the temps of a 400 or a 600. So it all comes down to your setup, not just your grow area. Temp of air going into the grow room, filter CFM, fan CFM, Cool Tube/Vented Hood, etc... all these factors come into play. if you're not going to use a vented hood or cool tube, you might run into issues with temps (Hot and/or cold). What is your setup?

I also have a DR100 and am currently using a 400watt switchable HID light. If you want to spring for a nice big blower and a vented hood then go with the 600watter, you could get away with it but not without superior cooling method. The 400 watter I have still gets pretty dang hot, you'll definitely still need cooling with whichever you choose, don't skimp you'll regret it later...