hey guys, i was just curious as to what is better to have, an intake with a fan, or passive intake. i put an intake fan on my grow box last night and my girls seem to be doing better (although that could just be in my head). however i was told on another post that passive intake is actually better. now im not even sure what passive intake is, but im guessing its pretty much just having holes for cool air to flow through, while the exhaust fan still pulls out the old air. If passive intake is better, then i may just put 2 decent sized holes for intake on each size of my box, maybe 3 or 4 inches across? any how, could someone please school me on this area of growing as im still new to the grow game? thanks!
intake fan vs passive intake
- Thread starter theceo13
- Start date
tsky
Active Member
Unless its a very large grow space passive intakes should do just fine and yes.. basicly they are just holes in your box probably best to cover them with some sort of fine mesh or somthing tho to prevent anything climbing inside. also try to make sure that once uve cut a hole in your box its somwhere lowish down so that light wont shine through it directly onto the plants during the dark cycle. im not sure really how much harm a little light would do tbh but better safe than sorry eh
purplehazin
Well-Known Member
yeah, passive intake only works well if you have a powerful exhaust fan. If you dont, then an intake fan might be needed to bring in fresh air.
Yes, oddly enough! Excessive passive intake areas are subject to external drafts and normal room circulation that could interfer with the controlled air flow that you are trying to create inside the tent. Refer to my answer on your other thread.
My basic info, on the other thread, came from a "Real" experiment that I saw - it went something like this. A greenhouse, fit with an exhaust fan, was filled with a measured amount of "smoke". The time it took to clear the air was measured and recorded. This was repeated many times, but each time the passive intake area was increased: x1, x2, x3, etc. Each increase in intake area resulted in a "dramatic" decrease in the amount of time it took to clear the air - up to 5 times the area (based on the diameter of the fan). Much more than 5x the area didn't produce much better results and it interfered with the air being directed in the desired direction. Frankly, I was amazed with the "5-to-1 Ratio" (it seemed like overkill), but I saw it with my own eyes! Of course, that's for maximum airflow efficiency, you may not be shooting for "Maximum".