400 watt HPS ventilation - 4" vs. 6" ducting?

So i just purchased a 400 watt sunlight supply sunsystem grow light and I am looking to get it air cooled. This is the hood that has the flanges on the sides, not the ends, of the hood. I have a limited flowering area, 3 x 2.5 x 6, and am looking to save space by using 4" ducting. Compared to the six inch ducting, how efficient will this be at removing the lights heat? I also plan to use CO2 so I am looking to have the temps around 90-95 to make it ideal.

First know the diameter of the flanges on your reflective hood. I would recommend using a 6" duct to it if it is a 6" flange. If not then just use a 4" duct. The wide the duct the more volume of air can be pushed to cool your light fixture. I myself would not go to the 90-95 degree area because at those temperatures you could stunt or completely cease growth.

calicat said:

First know the diameter of the flanges on your reflective hood. I would recommend using a 6" duct to it if it is a 6" flange. If not then just use a 4" duct. The wide the duct the more volume of air can be pushed to cool your light fixture. I myself would not go to the 90-95 degree area because at those temperatures you could stunt or completely cease growth.

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True, this would stunt or cease growth in normal environments, but the beauty of using CO2 is that it gives you a higher ideal temp between 90-95.

K, so I just looked on the site for my hood and it says it works with 4" ducting. My other question is what will it take to cut through my wall to make the venting ports? Do you think a rotary tool with a cutting attachment would do the trick? Something like a dremel tool?

a dremel will do it but its far from the best, if i were you i would use a drill to make a hole then use a jig saw to cut it out, i used a dremel once to cut some 3/4 rebar... it took me about half hour and 10 cut off wheels haha