Negative Pressure question

OKay, so i know there have been questions similar to this on here, but i have yet to find an answer for my specific set up
i have a fairly small grow box and i have a small fan, a little larger than a computer fan hooked up to it, and it is blowing air out.
here is my question. Does negative pressure adversely effect the growing process at all, or is it okay?

I have a grow room 2.5'x3.5'x6.5' with a 400 watt hps.I have a ten inch inline exhaust at the top sucking air out but only a 4" pvc light trap at the bottom effectively creating negative pressure.I tried to ask the same question with no reply,so i did it anyway.So far im only 2nd grows in and no negative side effects of any kind.As a matter of fact it creates a little breaze across my babies,to help evaporate the toxins on the leaves.Depending on your light and space the only way i could see any bad from it would be if you had a little room, big light with negative pressure that doesnt remove enough air volume (heat) causing heat stress.Hope this helps

here are some pics.The first pic is of a 12" form tube on one side of my 10" inline exhaust fan.second pic is my 4" pvc supply tube,and the third pic is of my babies.

DocEllis said:

OKay, so i know there have been questions similar to this on here, but i have yet to find an answer for my specific set up
i have a fairly small grow box and i have a small fan, a little larger than a computer fan hooked up to it, and it is blowing air out.
here is my question. Does negative pressure adversely effect the growing process at all, or is it okay?

Click to expand...

The whole idea of "negative pressure" is just to create a draft, not a vacuum. As your exhaust fan pulls air out of your box, you must make some provision for "input air" to replace it - either a powered or passive intake. For instense, with a passive intake - as the fan exhausts the old air, at the top end, fresh air gets sucked in at the bottom end because of "negative pressure".

The "negative pressure" is extreemly small because you're not sucking air from a closed container. You're just creating a draft - so there is no adverse effect!

thank you for your help, i have two 3 inch plants growing quickly in my little room, now
when i posted that i had just put them in soil.