My flower space will be a 2'x2'x56h" tent with a SS400 light; my mother/clone space will be a 2.5'x1.5'x3'h tent with a SF100. I have the option of drawing air from outside, inside, or both: outside avg air temp = 50F, ranges from 30-85 (Pacific NW); inside avg air temp = 65F, ranges from 60-85. I plan to use passive, HEPA-filtered intakes, with adjustable intake flaps so I can vary the flow from inside/outside. The fan will draw thru a carbon filter. I have several questions:

1. Will I be ok drawing air from inside only?
2. What size for the passive intake: 4" or 6"?
3. Is it possible to have a single exhaust fan to draw air thru both the veg and flower spaces, or should I plan to have 2 separate fans?
4. What size fan(s) should I buy?
5. What size carbon filter?

Welcome to the forums!

With less than 5' head space in your flower room you'll need to keep the plants very small with a short veg time. Also, until the clones are rooted or unless the mother/clone tent has separate light-proof compartments you shouldn't keep them with the "mother" plants. Unrooted clones should have a dark period, mother plants should not.

1) Yes, you can use inside air but 85 is still a bit warm so you may need AC in the room that the tents are in during peak heat and you also need to deal with humidity issues.
2) That depends on other choices. There is no one single right way.
3) That's two different questions. "Possible?" Yes. "Should?" Maybe.
4) Again, you have a lot of options.
5) That depends on other choices too.

Assuming the mother tent is "tent1" and the flower tent is "tent2" you COULD vent the top of tent1 to the bottom of tent2 using 1 6-8" carbon filter (inside tent2) and 1 6-8" fan outside of tent2 using a one or more 4" or 6" passive vent(s) in tent1. Is that optimal? No, but it should work.

You could use a single 6-8" fan with a Y adapter to exhaust each tent at the top with each tent having it's own passive intake at the bottom but each tent will still need it's own carbon filter and you cant change the speed in each tent so you don't have much control.

Separate (4-6") fans will give you much more control but then you also need two carbon filters and possibly two fan speed controllers. Luckily they're not that expensive and I'm a big fan (no pun intended) of overkill when it comes to ventilation fans so I'd go with bigger rather than smaller.


Hope that helps...

SME

Thanks For The Prompt & Informative Reply. I Tend To Build Things On The Beefy Side, So I Will Use 2 Fans. What Size Fans In Terms Of CFM Do You Suggest?

CFM ratings vary by manufacturer and model. The 6" Can Max-fan is about 335 CFM and the 6" Hurricane is about 425 CFM , I think. Either one is overkill so if you use a fan speed controller you can slow them down to make them more quiet. The better controllers will even give you separate day/night temps based on your settings. The Can Max-fan has a built in, manual, 3 speed controller but you'd have less temp control than you would with a better controller.

i have a 2x2x56 secret jardin, and i use a 4in active air with a phresh filter. i think my lap top is louder. as long my room ambient is around 70-74 it stays below 78 degrees. 6 would be slightly louder, maybe better if youre pulling from a long distance of ducting.

Yes, a 6" would be louder at full speed than a 4" but quieter and still more powerful with a speed controller. He'd also still have capacity for later expansion without needing to buy another fan.