Quick question regarding passive intake :)

[Smokerontheroof]

Hi guys, just a quick question regarding passive intake, my extraction consists of a carbon filter and extraction fan hung at the top of my tent and run outside into the room by a 4inch flexi pipe, for intake i plan to run a second flexi pipe at the bottom of the tent on the opposite side from the carbon filter and fan straight to an open window in same room, my question is what diamater of flexi pipe should i use for my passive intake to the window if my fan is sucking out through a 4inch pipe? Im sorry but i dont know the power of my extraction fan and can't check until tomorrow, any help greatly appreciated guys thanks

[Chew]

Hi guys, just a quick question regarding passive intake, my extraction consists of a carbon filter and extraction fan hung at the top of my tent and run outside into the room by a 4inch flexi pipe, for intake i plan to run a second flexi pipe at the bottom of the tent on the opposite side from the carbon filter and fan straight to an open window in same room, my question is what diamater of flexi pipe should i use for my passive intake to the window if my fan is sucking out through a 4inch pipe? Im sorry but i dont know the power of my extraction fan and can't check until tomorrow, any help greatly appreciated guys thanks

I run passive and the intake is the same size as my out. Any smaller and negative pressure is too much imo

[Smokerontheroof]

Ive heard so many different opinions im baffled, a good friend whos been at it a while with success says my intake should be half the size of my extractor to create negative pressure, is that right? My extractor is only 4 inches so 2 inch intake sounds a bit mad right?

[Skunky n funky]

Negetive pressure is really for smell reduction....... it has some positive effects on the grow environment, but more or less its for the smell control, so the filter picks it up instead of it getting discharged. I have positive pressure as we speak but I also am in veg, once I get into flower, I will kick on the filter, which will create some negetive pressue.

[Chew]

Ive heard so many different opinions im baffled, a good friend whos been at it a while with success says my intake should be half the size of my extractor to create negative pressure, is that right? My extractor is only 4 inches so 2 inch intake sounds a bit mad right?

If your extractor fan is a decent one, there’s no reason not to use the same size passive intake. It’s how I do it now and always have done. If you have a cheap crappy one, I could see that being an issue...

[Smokerontheroof]

Thanks guys, yeah im not sure what power my fan is i got it from a friend as part of a job lot i will check when back at grow if negative pressure has no ill effects and im going to want it for flowering i suppose im aswell just going with the 2 inch intake.. Will save me changing it when flowering and means i can get everything taped up and not have to mess around with it,, how would i know if it is too small? Its going straight to the window so im worried about bringing too much cool air in (its cold where i live) my temps are pretty solid now while only intaking from a warm room so any cold i bring will make big changes, opinions guys?

[Smokerontheroof]

Sorry to be a pain but anyone any ideas on a filter for my passive air intake? Dont want any bugs or critters getting sucked in! Cheers

[Bethmeg]

Does your tent not have a vent for passive intake at the bottom?

A mesh screen thing with a velcro flap?

Why not just use that and leave the window open a tad?

[ENGLISH_HERBSMAN]

if it doesnt you can always use some tights to allow air in and stop bugs
but as above most tents come with these flaps with mesh screen

[Nugsrus]

If it helps i run a 4” fan and filter as outtake and i have 5” ducting for the intake and still get negative pressure, as for a screen a pair of tights does wonders