Hello,

I have been using the setup that is pictured below for about a year now using over 400 watts of CFLs. I just recently spent the weekend adding the new exhaust to my closet. I now have it going through the wall and straight outside using a dryer vent kit. With this new exhaust option I now will be able to use much better lighting options.

My box is 40"L x 18"D x 61"H. I am thinking about a 400 hps in there in a vented hood or cooltube. The questions I have is that in the past i was using small makeshift carbon filters with computer fans and with this setup I want to use nice inline fans and nice filters. I was wondering what kind of cfm will i need to run with ducts from the filter through the hood and then out of the box to the outside? I was also wondering if a tent of the similar size would be a better option then this old box since its set up for random cfl placements? Any help or ideas would be greatly appreciated and sorry for the quality of the pics..........just have my phone camera atm.......

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bump..............

I would put a filter before the airtight light tube (on its intake) and put the inline fan somewhere between the filter and the outside, that way you can have a hidden (insude the box) filter and exhaust your box and light at the same time.
You could use a 100CFM fan, since your box is only 25sqft. (maybe less, if your exhaust stays cool that means the light is cool too)

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Cool thanks. I was thinking of getting a 4in inline fan that is around 140-170 cfm and was wondering if that would do it ok or if i should go with a 6in and around 300 cfm.

I have a 180 cfm in a 6.5x6.5x6.7 tent and it seems to be doing ok , But it does run constant . Just thought I would give you my size of tent to try to figure what you need . Oh by the way it does have a 4 inch outlet also .

I bet that would work great, because the fan is so close to the light and its the last stop before the air gets out of the box heat should never have time to build. 140-170 will do fine.
I would use 4"dia for that It will keep the air speed higher compared to 6"dia, which will help cool the light. Maybe go with something like those pyrex bread baking things on ebay, they are like $20 and 4"dia, cheap cool tube if you want DIY.

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Thanks for the help guys! Gonna order a nice 4" inline fan this weekend and get started on my new build. Think I will go ahead and get a tent as well. I seen one that is similar to my box.......think it is 62"x36"x20". Thanks again for the help.