todlow said:

Put your SFD ON TOP of your lid




I always cut my filters to fit my GE hole then permanently adhere the to the TOP of my lid w/ RTV:


I wipe off the left over myc and grain on the under side of the lid, put on a new jar filled w/ grain & PC.

NO reason to re-do anything.  Also, with this lid design, you don't need to put foil over your lids when you PC them. Since I stopped putting foil on my lids, I have less condensation on them when I take them outta the PC 12 hours later.

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Doc_T said:

Probably ok but sounds like a suboptimal design to me.

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13shrooms said:

While polyfill and tyvek are OK for GE they are not filters for anything thats why I use synthetic filter discs or Whatman filters.
poly and tyvek are way to porus to stop any contam of any kind period.



SFDs stop anything down to .3 microns and allow gas exchange.
They last forever as long as you dont puncture or cut them and my contam rate for my jars is ZERO since I made the move to SFDs.

If poly/tyvek works for you then thats fine but I would rather not chance it with pure luck.

Polyfill is good for monotubs or FCs with FAE holes where you use it to adjust your FAE and humidity not a contam barrier. 
You can pack it tight to hold your Rh or loosin it up to allow for more GE/FAE.
The whole point of poly is its an adjuster for Rh/FAE in FCs.

Tyvek of any kind is garbage IMO.
Its used the same way as polyfill but it is not adjustable and is used mostly for jars.
Its ok if thats all you can find but its not optimal in any way.


Ive used other methods that will work but not with the consistancy of SFDs.

G2G Jar lid prep;

3 - 1/8" holes with disc on lid inside threaded lid ring.







works great on 1/2 pints also


So if you live in a hundred year old moldy house or moldy environment like I do, it makes all the difference in the world for your success in colonizing Jars.

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Look at the first pic of the book in they quote and you will understand why polyfil can't trap all micro organisms, I am not saying that it wont work, but something could pass through it so you are taking a chance. If you don't have whatmans or SFDs it is probably the best alternative. My only concern is getting my SFD wet, so I was thinking of taking some free envelope tyvek and RTVing it to the inside of the GE hole to protect my SFD while shaking. But if the jar is properly PCd and contam free would the SFD being damp on the inside a little even make a difference?