Buchner funnel ethanol filtering

I’m trying to do the filtration on my cryo ethanol extractions in a 220 micron filter sock followed by 25 micron bag filter then into a 600 ml buchner loaded with celite and AC over a whatman #1filter I’m having problems with clogging from fats. Is filtration of 5 or so gallons possible with this setup at a reasonable speed. I’m trying not to have to upgrade but I’m considering a usa lab filter setup. Perhaps using graduated bag filters but they seem kinda expensive and single use. Another thought is doing a three layer filter cale with celite ac and celite replacing the top layer ever liter or so.

The 25 micron bag is the bottle neck. What kind of vacuum are you pulling? How thick is the celite bed? Cryo cold wash? Sounds like a good time to winterize and toss AO on top of the celite bed.

This is a big spoon I tossed ya. If you search for green grinch (winterizing nasty green etoh with ac/ao/celite) you’ll see the outcome.

160 bag
25 bag
Buchner with celite

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It seems to be going thought the 25 micron no problem. I’m doing 45 min cryo soaks in about 5 gallons of ethanol, mild vaccum around 25 in hg , and maybe a half inch celite bed. I’ve thought about playing with some AO but have never used it. I’ve read the green grinch post but maybe its time for a reread, I was hoping due to the temps that the flow was going to be a bit faster through the cake as the bag would catch a lot of the fines. I appreciate the input!

Before my panda, i was gravity draining 40gals of cryo etoh. In my 1st bag (160), it went quick. 2nd filter was thru a 25 bag. This was a full mesh 25 bag. Shit took FOREVER and had very minimal fines, zero biomass (minis very small fines). The 25 slowed me down 80%. Then I filtered thru buchner with celite.

My problem seemed to be on the celite I think a combination of the carbonated ethanol and warming of the solution which seemed to cause coagulationof fats on the celite. I’m almost considering ditching cryo till I get the hang of filtering because I’m definitely not using it efficiently and its kind of expensive where I am.

Don’t directly chill your ethanol with dry ice, getting carbonic acid into it changes the pH of your solution. In theory probably lessening it’s affinity for cannabanoids, plus acidifying the solution will likely give you some troubles making distillate isomers among other things.


Celite stops fines, not lipids and waxes. AO does that when winterizing.

I’ve always added di directly to my etoh and boimass. Granted my etoh has a 3.5ph, I still bang out +91% thc with 1% or lower cbn.

I’ve always done it this way, and do also at the lab I work at.

I found tricks. After every 3rd refill of the buchner, very carefully (after vacuumed all the etoh thru), scrape the very top of the celite cake to remove biomass fines. This will speed up the process. 3very 3rd scraping, add a little more celite


I will definitely try adding AO to my cake to see if it helps it seems like it could do the trick with a less fine structure, do you scrape the AO layer too? How much use do you usually get out of a filter bag? They dont reccomend reuse but it seems like it could be fine. Couild I titrate with NaOH to counteract the carbonic acid formation? I dont have a good way to chill without adding dry ice directly. I’m a pretty new processor so I’m reading as much as I can and I’m really grateful to this community.

I’ve posted my tricks many many times. With pics and laymens terms to help all.

Buchner funnel with fritted disc
Celite cake 1"
AO about 1/2"

Yes I scrape the immediate top layer of fines.

Use a wood dowel to pack powders while pulling vac. Pack down, run a little solvent thru. Rerun the filtered ethanol in the eryml flask.

I can manage 3x buchner funnels, all on a 3 way splitter with a welch wobl, and filter out 30 gallons in about 1hr.

Once you have a system in place, it’s like a factory assembly line.


I really thought I had this one after reading tons of posts and solving my last problems, in addition to not having AO for the fats my celite cakes were kind of wimpy and perhaps stuff made it though and clogged the #1 filter. It kind of sounds like to me a single 600 ml Buchner isnt quite enough to do 5 gallons in a reasonable time. I was using a gast moa for vacuum but Im not sure its enough for multiple funnels (The Wob L i got was missing literally all the seals so i had to send it back). Im considering making something out of 6 inch spools or biting the bullet and getting more glassware.

We have customers using different rated micron felt media (same as the media in our bag filter housings) in their Buchner funnels as a way to protect the carbon-DE combo. This way they just pull the felt media off the top and add a new one should it plug. They are not too expensive, certainly less than filter bags. Thanks, Greg

I rock a 3000ml buchner and a 5000ml eryml flask. Before was 3x 600ml to 3x 2000ml eryml flasks. All pulling -25hg on my wobble.

Gotta have systems un palce to rock 3 buchner funnels with minimal down time.

Do NOT use a 5000ml to a 10,000 eryml flask under vac. BOOM! Happened to me. It could have been the elcheapo china junk glass. I was only pulling -15hg.

What a mess that must have been! Thanks for the sage advice :pray:, im off to upgrade my filtration setup. Im leaning towards SS over glass because 3L funnels are kinda pricey for something I see myself breaking.


I actually anticipated it. Reason why it (10k eryml flask) was in a 20qt SS stock pot. I posted pics of that as well.

I’ve never broke a 2k, 3k, or 5k under vac, only the 10k one.

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What is AO?

aluminum oxide and as I understand it it should be activated and cannot be just any low grade alumina like blasting media, im ordering mine from carbon chemistry.


The waxes are a particles when precipitated, DE should be sufficient to remove waxes. While not ideal as far as filtration speed, a coffee filter can catch waxes.


AO is aluminum oxide and is also called activated alumina.

Here’s a link: Carbon Chemistry Activated Alumina | USA Lab

I am not sure what you are thinking or how you could get a seal on multiple bags. Are you pumping this through the bags as opposed to a vacuum setup? For sure, if you are winterizing, (and I use 5micron) your waxes are going to build up and you have to change your filter paper. We use large 100L buchner like filters and can do 5 gal no problem without having to change the filter do to the size of the filter (24in diameter) I am not sure if that is what usalab has or not. But for that style of winterization, it’s all about the size of the unit and micron of the paper.

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