Ventilation

[Billy]

Using 8 in outlet but don’t want to use an inlet fan,would I be ok just using the 3 eight inch holes in my tent with ducting on ....it is sucking in but is that ok.thanks

[kbag]

That would be fine Billy. Normally tent's have passive vents at the bottom with with a mesh screen to keep the bugs out but allow air in.

[bigbadbillybob]

3 x 8 inch holes seems a bit excessive tho as intake imho.
i would use 2 and put some old tights over the intake duct, or cooker hood filter,/ HEPA filter material, to stop pests getting in.

[Billy]

My tent is still sucking in even though I put 3 pieces of 8 in ducting on the intake sock holes,I know the pressure should be equal but is it ok ? Also the Velcro flaps if I open them will they let light in during flower ?

[bigbadbillybob]

the vents will let light in during flower yes, unless you make a light baffle. the tent sucking in is normal, thats what you want . its called negative pressure.

[seymore_budz]

I've only ever used outtake fans. Sometimes I've used inlet fans to pull fresh air from outside to control humidity etc but general rule of thumb is I don't bother. As for passive intake size, I like to times the area of my outlet by 2.5x. So if I'm using a 8" exit fan I'll try to have 20" of intake area. This doesn't have to be in all one area but I prefer to keep it low so the air passes through the plants on the way through.

Some might find this excessive but over the years I've found this simple equation works and doesn't put the fans under pressure.

[seymore_budz]

PS, Secret jardin does a kit that you can cut inlet holes in your tent and comes with a great light blocker. Really you can't see any light! Not sure if the flange would work on another brand though.

[IMO]

Heading into winter I would question do you need an 8inch fan on full belt?, on my next run I’m looking to keep extraction to a minimum, after listening to a podcast with a chap who iirc runs a grow shop who had done a co2 test and really minimal extraction is needed to keep co2 levels up, so the only reason to have more is humidity and temp so depends where you are in the world. Mad how you can have 3x8inch holes and it still suck in wow.