Interesting, good to know thanks! I think for my purposes any of them should hopefully be sufficient. I don’t see merv ratings on most of the filters I see so I guess it’s a bit of a crapshoot.
1 Like
well as you said there is a min standard, so i agree with you , why pay a fortune?
1 Like
Ya exactly that’s my thinking too. And now that Ive smoked some blackberry breath 
and thought about it I looked up the size of powdery mildew spores
Powdery Mildew - Puren Solutions.
According to this they are 1-3 microns in size so a HEPA would be big time overkill. I’m going to look up sizes for some other common pathogens (botrytis, pollen, bug eggs) and see what the smallest is. Hopefully there is a cheaper, more readily available filter that will cover all of them.
Weed: making me smarter, AND way dumber since 1995™
6 Likes
“Fungal spore sizes are typically between 2 and 10 μm”
https://apsjournals.apsnet.org/doi/abs/10.1094/PDIS-01-11-0064
“The size of conidia ranged from 5.0 to 9.5 × 6.5 to 12.5 μm (average 7.3 × 8.7 μm) based on 50 spore measurements.”
So it looks like all fungi should be covered by a filter that is effective to 1 micron or smaller.
Masks Help Filter Pollen and Prevent Hay Fever - Smart Air.
“Pollen particle sizes typically range from 10 microns up to 200 microns”. Cannabis pollen is 25-30 microns. Spider mite eggs are 1,000 microns according to wikipedia so no worries there.
1 Like
Go into the research done early covid on n95 alternatives.
2-3 layers of blue shop towels will get you nearly n95 at a fraction of the price. Lay it over intake, use a hose clamp to secure them, change monthly as routine maintenance.
4 Likes
The MERV/HEPA thing is a bit confusing, but according to this MERV 13+ will be more than enough to block all that shit, they actually show MERV 9-12 as being sufficient for pollen and mold spores, but I think I’ll try to go over 13 to be safe
4 Likes
Ya wtf eh? It’s weird to learn more about something and realize it’s way more complex than you imagined yet much simpler in some ways.
All these filters are essentially cloth/fabric/fiberglass or something similar arranged in such a way that small shit gets stuck in it while passing through.
1 Like
So far this looks like the best option. MERV 13 rated which should be more than sufficient. It’s a 20 square foot piece so a lifetime supply for $70
6 Likes
there is carbon filter sheets also there not hepa,but i use them over the insect ports on the tents, there black so it helps block light and they filter quite well it seems so far. And its a lot less money
1 Like
I have a friend who works in the environmental industry who has been giving me some advice about this. I was asking why carbon scrubbers don’t trap mildew spores because they’re on 24/7 and all the air in the room should eventually run through them.
Turns out they don’t, carbon is great for VOCs but not particulate. The masks they use for some types of projects have filters that have a carbon layer for VOCs and a HEPA layer for particulate.
He didn’t think they would necessarily trap pollen either which is something I always wondered about for breeding projects.
I figure if I’m going to do this and hopefully get my grow up and running again pm free I might as well spend the cash and do it properly. I ordered that fabric, it should be a enough for years so hopefully it works!
5 Likes
I use a 20x30 merv13. Same as my house ac.
For maximum flow and lifespan, I remember reading a tip about putting a merv8 in front of the merv13. These are the 1" thick variety.
I tried fabric pot material on a 6in vent. But airflow soon suffered as it collected chit.
1 Like
Oh man, you’re getting fucked. I can get that here in the US way cheaper!
I also found this nice washable filter at MERV 11 even. https://www.amazon.com/dp/B07PG5Q6NK/ref=cm_sw_r_cp_api_fabc_RZBYFb8DTAC3C?psc=1
5 Likes
Getting fucked on prices is a treasured Canadian tradition lol. Seriously though usually things are way more here and when you order it from the states tons of shipping etc gets tacked on so it turns out the same.
In this case I’ll save like $40 by ordering from US and A and it will still get here around the same time. Thanks!!
7 Likes
I have washable furnace heater filters.
Washable does not equate to cleanable filters lol. I have to pull it apart every 4 months, cut some new filter from the big sheet of filter I bought, and replace the filter between the mesh, washing does nothing other than make it wet and the dirt and dust turns to mud and stays traped in it 
2 Likes
Ya the rectangle style do not usually wash well, the most you can do is just hose off the outsides. Foam filter do wash up nicely. My sister’s house has some kind of electrostatic furnace on the filter, it’s made of metal. Every month or so they just rinse it off and it’s good as new.
3 Likes
Yeah mine was an electrostatic metal filter, now it’s just metal filter. I would rinse and blow it dry with a compressor, after a year it was so clogged l hardly got any heat coming through.
Luckily its held together with screws, but it’s a pain in the arse getting it back together again. Usually end up with the metal screen edges ripping holes in my fingers. I might run some duct taped around the edges next time it’s apart.
1 Like
Beats buying a new one every few months! If you have any of that metal duct tape it’s great for stuff like that.
1 Like
Oh man ! This really made me laugh, Killing me over here @beacher
4 Likes
Wouldn’t you just contaminate every time you open it up? Or are you just trying to limit exposure? Also, will the restriction to intake cause humidity to build in the room? Sorry, high as shit and all these questions popped into my head back to back lol
2 Likes