what kind of duct fan should i use for a 400w hps cool tube?

How many cfm's do i need to cool a 400w hps cool tube, and where exactly do u install it on side of bulb socket or free side?

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150-200. I run 200 cfm through my tube and my 400 stays cool to the touch. I use a can max 6 incher and keep it on the low setting. I have mine installed on my carbon filter and ducting running to the tube. Don't really matter which side it comes in.

Edit: I actually ran my 400 for a while on 105 CFM and it worked decently, but got a bit hotter than I would have liked. I couldn't touch the tube for very long before getting uncomfortable.

This is a loaded ? . Are you pushing it thru a carbon filter or not. I just buy cheap inline fans for $25 off amazon and they work great but I'm not going thru a carbon filter. If using a filter that will dictate the power you need. As far as hooking it up, I use the open end because there is nothing in the way and you can direct your fan to suck or push what ever is best for you just by turning it around.

You want to probably run an inline fan not one of those duct booster fans. Get somthing that will pull through a carbon filter if you end up getting one which id also reccomend. And it goes....carbon filter-fan-duct-light-duct-air out. Air intake on bottom and out on top.

Get an in line fan. I use to run a 400 and upgraded my old 200 something cfm 4 inch with attached carbon filter. It wasn't doing the job in the summer so I went over kill and now run a 460 cfm 6 inch through my cool tube. Temps only rise about 7 degrees in the tent when the light is on. Works great and wish I had gone big my first go round.

I run with 1000 watt light, i use a 440 cfm in line fan exhaust for winter and i also use 2x can fans intake (~100 cfms per) in summer for the heat problems.
hope this helps
gl!

I only run a 400w but I went with a 6" 450cfm can fan. When I compared the 4" fan from htg to the 6", the 4" had half the cfm and used almost the same power and the price was only like 25 $ more. So the choice was obvious, get a bigger fan than what you need and buy a variable fan switch, that way you have a very simple efficient way to adjust temps, and airflow.

If your ducting is short with no bends a cheap inline fan will do, if the ducting is long or has a lot of bends then you will need a centrifugal fan.

I have a 165cfm fan now but the blades are plastic will this melt my blades being by my 400w bulb?

And in thinking of buying the 6in carbin filter combo from VenTech comes with a 6in 240cfm duct fan.
has any tried this filter? and will it be enough for 2plants.
Thanks for everyones prompt responses

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