Small Tent and Vent Issue

KDiaz said:

I have a 20"x36"x5' that I have 5 plants in. I am looking into a ventilation system for it. I am looking at HTG as a reference. Obviously 2x3x5 is 30 cubic feet. Divided by 5 for the minutes the air should be exchanged gives me a fan size of 6cfm. So now the real issue, I was looking at inline fan and carbon filter combos. The growbright 4" inline fan/filter combo moves 170cfm which is way overkill, by that math that will do like a 10x10x8 room. So my air would be exchanged every few seconds. I also look at the 4" inline duct fan which moves 80cfm but they say its not compatible with a carbon filter. Is this true? I see the filter has a minimum cfm of like 150 or something? so what do you recommend?

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pixelpusher said:

you did your math wrong friend. I have this same size tent. it's basically 27cf. Now you definitely don't want it to take 5 min to exchange the air. More like you want to do a minimum of 5 air changes/min. That makes 27cf x 5min=135cfm

Also, there is something called static pressure in vent systems. This is basically the pressure that needs to be exerted to overcome the propensity of the all that air in the tent to not move. That pressure needed to move the air increases as things like ducting and turns in the ducting are added.

So in the case of a vent fan that says 135cfm, this is referring to the amount of air that fan will move when it is not connected to anything, or 0" static pressure. Connect it to a few feet of duct with a right angle in it and pulling through a carbon filter and then your looking at more like 1/4 to 1/2 of the rated cfm.

Long story short, I use a Soler and Palau TD-100 rated at 100cfm. However, they have a decent static pressure rating and can get the air moving. I vent directly above the tent so no turns in the ducting and it is working for me at this point. I'd go for th TD-200x if I as going to do it over again.

Good luck!

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