Intake fan

I totally know the importance of an exhaust fan, likely with a carbon filter. I also know that you need some sort of fresh air intake. So much is talked about with the exhaust and carbon filter, etc, but I just don't read much on the intake. What is everyone using? I expect that an intake fan should be equal to the exhaust CFM rating but do you guys use the same expensive fan for intake as exhaust?

Most dont use intakes, or if so they use one that is rated lower than its exhaust cfm to keep negitive pressure or to balance out the pressure from the carbon scrubber.

With a tent most people use a passive intake (down low) of 2 - 2.5x the surface area of the exhaust.

Negative pressure is only really desirable if you are concerned about odors...

The advantages of using a filtered intake/makeup air fan (to create a positive pressure) include:

1. Not having your tent walls cave in due to the negative pressure

2. Knowing that all of the air entering the tent is being filtered. (With a negative pressure, you'll be pulling in air from anywhere it can get it.)

(edit) 3. Your exhaust fan will move more air not having to work against the negative (static) pressure.

I do not run an intake fan, just a hole cut in the door for a passive intake and make sure no light can get in.

Seems that it is always a good reminder to be cautious of light. I appreciate that.

Without being a person that really knows anything at all, it would seem that if the walls of your tent are cavitating, That would be an indication to open your passive intake port just a little more, correct? Or if using an intake fan that it should be rated for a little more CFM?

MrPuffTuff, addressing your point #2, what are some of the benefits of a filtered air intake? Is it mostly to decrease mold spores, bacteria, viruses and dust or are there other reasons? Do you believe there is a tangible benefit to using a filtered air intake?

While I am legal to grow, I do want to be cautious and respectful of odors during flower and the drying process.

Some really valuable stuff here, guys. Thank you!

I have a 5x5 tent I run two of the exact same fans, both set at the same variable speed setting for desired humidity and fresh air transfer. Intake is set low and the exhaust is set up high. Both ends have prefiltered carbon filters.

Clumpyoyster said:

I have a 5x5 tent I run two of the exact same fans, both set at the same variable speed setting for desired humidity and fresh air transfer. Intake is set low and the exhaust is set up high. Both ends have prefiltered carbon filters.

Click to expand...

Do u run them 24/7?

Yes

Do you guys find that some black pantyhose (single or double layer) are good enough as an intake filter to help keep things like bugs/mites and dust out? Or is a dust shroom really needed. I guess I could ask the same thing about pantyhoes on the vent set up in a window?

I was also struggling a lot with the intake air, as the tent was shrinking and sucking a lot, while the exhaust fan was on the minimum.

I was thinking in adding an additional intake fan with a flexible tube, going from a place near room's window to the grow tent.

At the end I have only opened by half the two square side windows, in order to recycle the air. Also, I added a small fan inside the grow tent that helps with the ventilation. My average temperature is 27-33 Celsius degrees and also 60%humidity.

I keep the rooms windows, opened all the time to bring inside fresh air and plenty of CO2.

This is the 3rd week and things seem to go good.