Lowest Micron With GL Fittings?

I just purchased a 2Liter setup, had been running on a 500ml with an ebay pump for over a year. The pump I got actually pulled down to 300-500 but never lower, What im trying to figure out is if it was the pump or the GL fittings? Now with my 2Liter I added a cold trap and upgraded to a Alcatel 2021 SD.

What my question is what’s the lowest micron you’ve achieved with GL fittings and what should I expect! Can I hit <20?

not the right question

FIRST test the pump without all the extra added nonsense…

you want the “blank off value”: which == the level of vacuum you can pull with nothing but the gauge attached to your pump.

then compare to your dry system. that will tell you if you have leaks. you can then locate said leaks. either with a spray bottle of ethanol, or a tank of He (for the little ones your etoh can’t find.

if you squirt ethanol at a leak, some will get sucked it. by evaporating it will raise the pressure level.


Okay I have a Supco Vacuum gauge, it needs to run through it to get a rating, I have a hose connecting it to the pump and then i just blank down the other side with my finger. I cant seem to get that too hold. but I was immediately dropping to 200-300 micron and then slowly lowering but then would jump. Going to try and find something to really bite down on it. I should have a micron reading later tonight

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you can close off one side of the gauge and it works fine. just need the right cap. don’t have pictures at hand…

and running your vacuum path through that gauge is not helping your distillation through-put one bit. locate it as a dead end. measure the vac, don’t throttle it through a tiny orifice

Edit: here ya go…

1/4” flare fitting cap from home despot does the trick.


All gl fittings. Using the roughing pump first and then switching to the big bitch. Alcatel 2021 sd. So stoked! Will update microns soon. Have a second cold trap coming in, couldn’t wait let’s go!

So happy to be done with the 500ml spd !

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Its gonna be more about the amount of “air” you’ll be able to pull thru the gl fittings. Which if I remember right is 14cfm.

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I believe my pump does 14.6 or something. That was the one thing I was worried about! Fingers crossed. My 250$ eBay roughing pump is pulling 1200 micron! Damn I’m impressed actually… that’s without heat though but still!

Read on that plate what micron it can pull down too, those from harbor freight pull 250 or less brand new. There garbage pumps and not the best for a roughing pump but use what you got til you can upgrade. I would get another alcatel off ebay and use that as a roughing pump paired with the other one, its at least worth rebuilding an alcatel.


Pulling mains now at 205 mantel temp, start pulling at 200 but this is my first pass so I’m impatient. Micron gauge reading 590 and slowly dropping by 2’s. Not quite sure what the problem is, think it’s gl fittings.

Down to 350 microns on mains

My question is what can I improve on for microns?

Would another cold trap help microns(have one on the way)

New vac gauge?

Can I put gl18 on it and will that make it better?

What’s the next step up from gl fittings? Do I need to buy all new glass for full boar?

Yes full boar is next step

Another cold trap might help, try decarbing under vacuum in a roto or reactor that’ll help remove some terpenes before you hit the spd

Less to remove = better vacuum

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If you dont have to loot to grab all new glass ware you can go close to full bore for cheap with a few glass pieces


Full boar probably won’t help him without a larger head though

34 45 a atleasr since most full boars are 29/42 at the trap

There’s some good Chinese glass manufacturers on here who make some dope full boar spds

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Sweet baby jesus that looks like an alien space ship… man right when I think I’m a big dog I see shit like that lol…

I’m leveling up though! Appreciate the replies

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are you running with a solvent in your cold trap?

I actually just put some iso in it later in run. Not all the way though does that help quite a bit?

I’ve always had problems with my bf to head connection. I use dow, Just bought a ptfe sleeve first time trying it and it dropped enough for me to be content for the night. Still running and now my microns climb from 350 to 450. Really trying to find weak points but don’t have helium and can’t see anything as of yet. About 3/4 of the way through the run. Since my micron was high I tried to stay as low as possible to keep some color and it’s taking foreva…

Would running a second pass at like 200-300 help with color at all?

you just need the bottom filled, i usually fill up a few inches of depth, if you fill it up too much, the bubbling from the dryice sublimating will make your spill your solvent from the top, and then solvent will drip everywhere and thats no fun.

this is the trickest joint, just use a ton of grease, dow isnt the best. get some apzion H or similiar, if you find it leaking mid run sometimes you can just apply a bead of cheap grease, like dow, to the top of the joint and itll seal it up usually, this can be done mid run, at temp without tearing it down. this can be applied to any joint.

if your depth rises mid run it may just because there are more volatiles in the system and your pump doesnt have enough CFM to overcome whats actively being evolved from the boiling flask. Something that might help a little bit is putting a bowl of solvent and dry ice underneath the receiving flask of your cold trap!

a few things you can try tho;
A. change pump oil
B. run your pump with flushing fluid, clean up some of those internal surfaces, before putting fresh oil in and distilling.
C. replace GL fitting orings,
D. replace vacuum hoses
E. teflon tape the outside of all the joints, apply a bead of grease to the joint first, like described above. An ugly and annoying solution, but it works in a pinch

also you dont need helium to do a leak test, you can use any volatile solvent to accomplish this, i usually use meoh for this.

potentially, 200-300 is still pretty high for good “gold” your going to need to go deeper or your going to have to apply preprocessing techniques like refinement filtration to your crude material predistillation.

is this CBD or THC? hows this extracted, what processing steps are you applying? is the material decarbed?


Wow so much great information there I don’t know what to respond with first.

Firstly though it is a small leak at bc and head because your trick with the grease dropped my microns back to 350and bows it’s kind of erratic +/- 10 microns so I’m thinking that’s it.
I do a cryo ethanol wash no winter, filter through t5/carbon. Roto then decarb then spd

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That’s a good sized pump for a 2L

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That’s why I’m kind of not happy with the 300-400 micron. There’s something going on I need to fix it!