I Don't Have a 600w. But, I Do Have 430w. & 1,000w.& There Is About 10*Degree's Between Them..,,,If You Add A 1,000w., You Will Won't To Add A Cooltube...I'm In The Process Of Putting All My 1,000w. Light's In Cooltube's, & Have Dropped My Temp's 20*Degree's....,,,,,Hope This Might Shed Some Light On Your Question????,,,,,,,,Later,,,HATCH


