intake fan filter suggestion

I have a small 6" booster fan (cheap home depot type) pulling outside air into my small grow closet. It was suggested to me here and elswhere to put a hepa filter on the intake to keep spider mites out. The window I am using is 15' above the ground, but I am still concerned that spider mites might get airborn(?)

#1 Hepa filters are very expensive and I just spend a bunch on a "real"exhaust fan, charcoal filter, flame defender, speed controller, etc.

#2 the hydro store I went to said their filter ($120) would pretty much block the air from the cheap booster fan I have set up, so I would get no fresh air.

#3 I am switching to complete passive intake once the weather gets colder and reducing air flow would be bad.

My idea:
I read that spider mites are about 1 millimeter. I can buy micro filter pads at aquatic stores pretty cheap. These go 50 microns (1/10th of a mm*). I think this would block mites and still allow good air flow.

Any thoughts or advice would be greatly appreciated. I have never had mites and I don't want to start now.

*my math skills are bad, but a micron i 1/1000th of a mm. So 100 microns would be 1/10th a mm I think. Still smaller than a mite. Is this right (math people)?

pair of tights/stocking on either end of the ducting.

ROBSTERB said:

pair of tights/stocking on either end of the ducting.

Click to expand...

seriously? I thought about this but it seemed too easy.

Your math seems to be spot on. However you have a few other things to consider. First off mites can be smaller than 1mm, especially larvae and immature/young. That said 50 micron should be adequate for stopping most all insects.
More of the issue imo though is mold spores and bacteria which can be as small as 1 micron in some cases. Check out the following link on organic air hepa filters : http://www.bghydro.com/BGH/itemdesc.asp?ic=AFAAIF04&Tp=

Leggings/stockings are probably greater than 100 microns even doubled up, better than nothing though! Just remember, the floral print on the garter faces the front.

what about vacum cleaner bags. Some are hepa. Maybe cut one up and wrap it around your intake?

thanks to all.
the air hepa filters are what I was checking out at the hydro store = fan wont work. Funny about the floral print.

I also thought about vacuum cleaner bags but if you think about it, when turn on your vacuum, the bag fills up with air but nothing passes through it. So I doubt I would get any air.

I will probably just go with the 50 micron thing. It's cheap and will help. I will just pray for no mold.

Also, vacuum us a funny word. 2 u's together. that's nuts.

Mites can be less than 0.002 inch or 0.0508 mm or 50 microns. Thrips are about 7 microns.
There are some good insect screens made but I don't know where to get them cheaply. Best bet would be " No-Thrip Insect Screen" It costs less than $1 per sf but there is a minimum charge of $20.I need some myself but I'm too cheap to pay the minimum. Wish I could find it somewhere else. Read more here: http://www.greenhousemegastore.com/product/no-thrip-insect-screen

Ok...after saying all that, your original idea of a micro filter doesn't sound too bad

EvlMunkee said:

Mites can be less than 0.002 inch or 0.0508 mm or 50 microns. Thrips are about 7 microns.
There are some good insect screens made but I don't know where to get them cheaply. Best bet would be " No-Thrip Insect Screen" It costs less than $1 per sf but there is a minimum charge of $20.I need some myself but I'm too cheap to pay the minimum. Wish I could find it somewhere else. Read more here: http://www.greenhousemegastore.com/product/no-thrip-insect-screen

Ok...after saying all that, your original idea of a micro filter doesn't sound too bad

Click to expand...

I have found many different article on how big the mites get, and there are different varieties. THis one is what I used since it is from WSU and I am in washington:
The adult female is about 1/60 inch (0.44 mm) long, whereas the male is only about 1/80 inch (0.29) long. The quiescent (larva) stage is about 1/12 inch (0.20 mm) long. The protonymph is oval and dark green and has four pairs of legs. The female is 1/100 inch (0.25 mm)

that being read, I still think I will be good with a 50 micron screen -- or at least that is as much effort as I am willing to put into it.

rbico said:

I have found many different article on how big the mites get, and there are different varieties. THis one is what I used since it is from WSU and I am in washington:
The adult female is about 1/60 inch (0.44 mm) long, whereas the male is only about 1/80 inch (0.29) long. The quiescent (larva) stage is about 1/12 inch (0.20 mm) long. The protonymph is oval and dark green and has four pairs of legs. The female is 1/100 inch (0.25 mm)

that being read, I still think I will be good with a 50 micron screen -- or at least that is as much effort as I am willing to put into it.

Click to expand...

Ok..I didn't know about that mite. We have the two spotted or red spider mite here. Apparently they can be much smaller.
Anyway, They should be about dormant there anyway, right?. You shouldn't have to worry too much until it warms up again.
My intake is way off the ground too but I only use it when the outside air drops to < 50F...not many bugs out then.