Co2 extraction problems

I am currently having a few issues with my Co2 extractor and was wondering if you if you guys might have a solution. As of right now I am getting a lot of water in my crude oil and have taken my machine apart and put it back together several times to try and find the source to no avail. Anyone have any ideas what it could be?


Are you oven drying your herb?

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I am not, no. However with the amount of water coming out, it’s lead me to believe that it’s somewhere in the system itself and not the product I’m running

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Can you ask you gas supplyer to list the water content in your gas?

Its worth checking the purity of your CO2 but It’s probably from your input material. Cannabis trim can have anywhere from 4-8% moisture content. You should dry and decarboxylate the biomass for more efficient extraction. CO2 extracts D9THC far more efficiently than THCA.

What type of system are you running?


are you reusing the same co2 forever?

Hydrosol in your wax can come from a few places. If your thermal dynamics are off ( temp on solvent chamber or expansion chamber ) your gas will not phase shift correctly and carry moisture over into your fraction or collection cup. The best way to trouble shoot to see what it may be is to decarb your start material to eliminate that possibility then next check that your parameters are not only set to correct values for your target set points but that the machine is actually achieving them… do you have temp gauges or plc to monitor run data?


Hey guys, Just a quick update. I managed to solve my problem by putting a coalescing filter on my machine. Now that I think about it I have no idea why there wouldn’t have been one on it in the first place. But ever since I threw that bad boy on I haven’t had a problem with water in my crude at all.


My lab currently does not oven dry our biomass pre-extraction. Water has been annoying in both our CO2 and ethanol extractions, and we would of course be happy to improve our CO2 extraction yields. I was hoping you could answer two clarifying questions.

  1. Do you worry about losing terpenes during the oven drying process? Our CO2 oil is for vape pens and taste is obviously very important.
  2. do you oven dry before ethanol extractions to reduce H2O contamination of your ethanol?


Most processors will refine the CO2 oil further into distillate so the Terpenes are of less importance than the cannabinoids. With the lower end mixes of biomass that most processors deal with it’s not worth the effort to save the Terpenes. The best route from there is to reintroduce commercially available Terpenes back into the distillate for vape products.

If you have good input material that is strain specific you can use a vacuum oven with a cold trap to collect and reuse the Terpenes from the biomass. You could also try steam distilling the biomass prior to going into the oven but it might be more challenging and time consuming to scale.

Drying the biomass prior to your extraction should help limit adding excess water into your Ethanol and final products. There are also ways to remove excess moisture from your ethanol using a Zeolite as a molecular sieve.


I really like the vacuum oven cold trap idea for trapping terpenes. We were looking at doing that on our CO2 machine to reduce contaminating our condenser with volatiles.

What kind of ethanol recovery do you get from Zeolite filtration? is it capable of taking 90% etoh to 95%? 80% to 95%? Currently we’re looking at dewatering systems for large solvent volumes but simpler is always better, and usually cheaper.


One other idea for saving those terpenes, you could consider doing a ‘terpene run’ on the material first, then oven drying/decarboxylating, then your primary cannabinoid extraction. I have unbleached cotton bags that I put my material into for quick loading and unloading of the extraction column, I throw it in the extractor for around 1 hour with a slow flow rate at a cool temperature. Using this method I have seen my oils average around 7% terpene content in the end. I do generally get some cannabinoids and small amounts of water coming through but the water is easy to separate. I am using hand trim and popcorn nugs though, I don’t bother with the terpenes from machine trim, in that scenario I source outside terpenes and blend in at the end like what @KSlabs was recommending.


This should help you:


Theoretically you can remove the water past .999% with dehydration. In practice you won’t achieve this, the air we breathe has water in it. The etoh is very hydroscopic, it loves to grab free h20 whenever it can.

mind sharing how you are separating the extracted H2O?

Probably a sep funnel like most hydrosols.

This is an amzing resource, thank you very much for sharing!

A seperatory funnel should be great for the larger batches. I’m only running 2-6 pounds on average through my current system so I collect in a 100mL graduated cylinder. The water is heavier and sinks almost immediately, occasionally some will stick to the glass and I will use very gentle heat from a heat gun to coerce it down, then I pipette the water out. Something interesting I have observed and would be interested to get opinions on… Generally, I have clear water coming through but occasionally it forms, I assume, hydrosols, milky opaque water. If I leave the terpenes and water (suspected hydrosol) to sit for a day or two the water becomes clear. Are the terpenes being reabsorbed from the water into the terpene rich fraction?


Hey @Stevesgoodsonline,
Glad you got the problem solved, depending on your operating environment, specifically with regards to humidity, be sure to check that thing regularly and let it dry. My air compressor is near our veg room so if we have a rainy day and a watering day overlap I can often collect quite a bit of water out of the filter bottom even with the air dryer on the compressor running :droplet:. If I’m not running the machine overnight I’ll open it up to let it dry completely, especially the filter itself.

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We process a separate fraction run for terpenes and yield 2-8% depending on the harvest date of the flower and the companies we wholesale through. Then Decarb and collect THC from a final fraction. If you wanna collect terps its best to remove them first, water comes with them under that solvent density so you can easily separate the water from the terps with the help of a sep funnel and a freeze dryer. Im not sure what Co2 extractor you are using but we purge the storage tanks on ours monthly to remove condensed H20 from the tank. Seems lately like the terp pulls remove a solid amount of water from the flower. We decarb in a Cascade decarb oven, no vac. The crude is gorgeous and tests above 80% out the gate.