Troubleshooting 3 Stage KDT10

Hey all, I’m looking for some insight into dialing in my system on the 3-stage KDT10. I have been running this machine for about 4 months now, and could use some pointers on parameters. I understand that with a triple stage system you should conceivably be able to do a Terp Strip, 1st and 2nd Polish on 1 pass. However, try as I might to fully decarb the oil and remove all solvent, immediately when I feed the oil into the 1st stage (10 hz) I start losing vacuum significantly. I’m lucky if it hovers around 9x -1. It begins to distill in the 2nd stage, but the color is not what I want.

Previously I had gotten into the habit of doing a faster terp cut in only stages 1 & 2 (20-25 hz feed), then rerunning the entirety of the oil for a 2nd pass. This seems to fix my vacuum problem, I’m assuming because the 1st pass removed any residual solvent. It doesn’t remove all of the volatiles at this speed, but makes the oil much more compatible with the vacuum. The problem seems to be my crude. We are extracting with a CUP 30, then evaporating ethanol off with a Maratek C100.

I have kept the oil under vacuum and high heat, stirred profusely and thoroughly decarbed. I need to make this process as efficient as possible, and hoping to use only 1 pass on this machine.

Currently my operating temps are as follows:
EVAP 1- 158 C (All Passes)
EVAP 2- 178 C (1st Pass), 168 C (2nd Pass)
EVAP 3- 185 C(1st Pass), 175 C (2nd Pass)
Condenser 1- 0 C
Condenser 2- 95 C
Residue Bath- 150 C
Feed Tank: 100- 130 C
Cold Trap- Set to -50 but typically hovers around -38- -42
Residue and Distillate pumps typically all set to 3 hz (they won’t run lower) but with ball valves usually at an angle to try to slow transfer further.

Typical Vacuum Achieved.
Stage 1: 1x -1
Stage 2: 7x -3 (with turbo)
Stage 3: 8x -4 (with turbo)

Roller Speeds:
Stage 1: 55 hz
Stage 2: 40 hz
Stage 2: 40 hz

Any input on this would be greatly appreciated. I’ve been extracting for several years but I’m a bit of a novice at distillation.

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if your not decarbing at 150c under vac for a WHILE your not getting all the volatiles out. that was my first issue to resolve


Okay much obliged. I haven’t been doing it quite that hot so will do!

the larger the thermal mass you are decarbing the longer id leave it once its up to temp to devol and strip ultra light terps. i do like 2-3 hrs once i hit 160c on my reactor for 15-20L. ive tested at diff temps and times and ive noticed very minimal degradation


i do 160ish on terp, 180ish on first dist, then drop to 170ish on my final and get the best results but all those are dependent on your feed speed and max vac depth at said speed. cbd btw


Terrific I was slightly worried about degradation at that temp.

everyone is…but thin film and vac will allow every molecule left in your crude to be expressed. better to lose a point or maybe 2 if it means consistent results and much more throughput. just my opinion. id suggest overdecarbing the shit out of a small amount of crude and testing it if you can afford the r and d analytics cost. i saw 1-2% maximum loss but i also use a an agitated reactor under vac. what you decarb with may make this vary

Well at the moment we have 4 CVO-5-L Cascade Sciences Vacuum ovens. I already know these don’t cut it. Just checked they only go to 250 F. Also recently we have tried to cook the oil down more in the Maratek. However we have a new decarb skid from Chemtech Services that we are waiting on a tech to install. Hoping this will be a game changer. These have Julabo heaters I’m sure we can hit the temp in this.

Go to the store and get a convection hot plate and some steel tomales pots to decarb in

You cant get hot enough in that oven for proper decarb

You need to be between 300 and 700 microns for the terpene strip

Your settings are right I’m running almost exactly what you are just a little warmer because I have a 2 stage


Awesome will do. Thanks for the advice!

This will sound a bit odd but i found out the best decarb method is actually doing it twice. Meaning i will decarb one day, let it sit unheated overnight and i will decarb again for an hour the next day or until no more bubbles/smoke again are coming up.

Also i wipped the crude unorthodox till they had no bubbles in the hopper also.

Tip: take a thermometer probe and check measurement on the top portion of the crude in the hopper. When your probe temperature equals your hopper temperature your ready to roll.

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We use induction hot plate at 125C with food grade stainless 20qt pots. With a stirrer, make sure you decarb all the little coke fizzles out.


I actually meant an induction hot plate like what @Boomtownpharms said, just make sure your pot is induction comparable


Any thoughts on wiper speed? I’ve been experimenting from 50 hz all the way down to 10 hz. I understand you get more vapor with higher wiper speed, but will you pull impurity at a certain speed? And at too low a speed I’m sure it will not even distill.

@anon42519203 this is my co-worker’s post, we both are dialing this unit in

Honestly, 0.5 - 1 torr should be completely adequate for terp strip at 158.

Can you restate your issues? What is the purity of your final product? Are you moving too slow? Is it the color only?

I think your distillation vacuum levels are stellar. I’d kill to distill at 10e-4. My KD10 is killing me lately.

Edit: your condenser temp on the first stage are pretty frign low though, I usually run 20-40C

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We’ve consistently been getting 85-90% THC, 92-95% total cannabanoids. Typically copper or gold in color. At times though it’s more red than I want, or the consumer does for that matter. Transferring from one stage to another as slowly as possible. For reference, the pumps we use won’t go lower than 3 hz, so I open the ball valves as little as possible for stage transfer. One of our real problems is that we don’t have a proper purging method to prepare the oil for the KD, leaving too much solvent? volatiles? The decarb skid I referenced earlier in the thread will be running soon, but for now I’m trying out different work arounds. As it currently stands, I’ve gotten into the habit of running a faster terp cut, 20-35 hz feed, through the first 2 stages. I then empty the “bottoms” (just the oil that I cut terps off of), back into the feed tank for a proper first pass. This is the only way I can get my vacuum to hold properly, cutting terps first and then sending it back through to begin distillation. I know i need to be decarbing at high heat under vacuum, but for now this is what I can do.

Hey I’ll drop you a few tips to try testing with, and please anyone let me know where you might tweak this.

Your decarb issue sounds like the major reason for a poor first pass and vac level issues, but adding a second cold trap between the element and your vacuum will greatly improve your vac stability. I run a KDT 6 and I added a typical $500 Dry ice & isopropyl cold trap in between the vac sensor and the vac pump. Avoid adding too much extra hosing tho, as this will decrease your overall vac level.

Your first pass Evap temp is too hot in my opinion. Unless you have a fair amount of pre-distillation processing, which it doesn’t sound like you have, then you are working with a complete Full Spectrum crude which has ALOT of volatiles between 90 - 150C. Without a relatively long, hot decarb you are releasing all of those compounds at once under the intensity of high vacuum. I would recommend a 130 - 145C Evap temp for Terp stripping. Do this with a slow feed rate and you will strip off almost everything that is “light” enough to pass a cold trap and enter your vacuum. The condenser under these conditions can be as low as you like.

Your second pass should be the hottest, not your third. The way I distill in 3 stages is ~140C to evaporate off the light stuff from your crude; then ~180C to evaporate off the desirables from the heavy undesirables (waxes and such); then ~155 - 175C to isolate the desired compound or range.

The darks and the reds your getting are either the Heavy compounds that your accidentally including by evaporating at high temperatures and collecting; OR your temp is so hot and your vacuum is so deep that you’re burning some of your desired compounds. 8e-4 vacuum will lower your desirable boiling points to below 180C.

A trick to distillation, that proves absolutely necessary with the KDT units in my opinion, is a hot condenser. On the first pass the condenser should basically act as a preliminary cold trap, 0C is great. But on the second pass it should be hot, as in 100 - 120C. I only have a single stage so anything that passes the condenser goes either to my cold trap or out of my vacuum exhaust in the form of the foulest smelling essence known to our lab community. That being said, with a condenser in this temp range I have little to no material collecting or any foul smell; so all that is being evaporated is being condensed and collected. The third pass should be hotter than the second. This is how you properly isolate your desired compound. With your vacuum depth being 8e-4, you will collect the purest product somewhere between 130 - 160C on the condenser. Exactly where in that range comes from practice, close observation and good math; not to mention it will vary about +/-5C with oil quality and how well you performed stage 1 & 2, but reading a vacuum gauge intelligently will tell you everything you need to know about what’s happening in the internal reaction.

Keep your feed tank at 125 - 130C consistently. As long as the oil residence time in the feed isn’t several hours, this will aid you with your decarb problem. I’m not suggesting using the feed to decarb. I do a quick decarb on a hot plate, just like the above members have mentioned, up to ~115C until MOST bubbles settle. The high speed of my stir bar is the secret to making the decarb quick. I then load the feed with this already hot oil and watch as new little bubbles begin to rise. For another reason, that’s too much of a tangent, I don’t fully decarb like tradition says. Hint: CBDA doesn’t crystalize. Back to the point; a hot Feed tank will already start to separate “lights” from “heavys” which will aid with your terp stripping. Hot oil also flows better and isn’t subject to temperature “shock” which can create azeotropes that are harder to separate/isolate.

Using a Maratek C100 properly should 90%+ solvent so as long as you are confident in the way you’re running the parameters. So don’t think in terms of solvents as the issue when doing distillation with hot temperatures, they don’t want anything to do with your heat.
The problem is a chemistry one; dealing with solids that want to be solids but your evaporating them. Terpenes are a nasty beast when heated, they can stick to everything and solidify & collect where you don’t want them, ever. Think in terms of tracking your vapors. Consider how temperature ranges/differences will propel or attract compounds. I figured out distillation parameters by getting super high off edibles and meditating in front of my machine while it was running; I DON’T suggest this kind of behavior! I imagined myself as a certain compound (knowing it’s characteristics like B.P., polarity, molecule size, etc.) and thought of what I would do if it was me. For example, if I’m in a fucking furnace haha I’d probably get to the coldest thing near me asap; OR I might find a larger, tougher molecule to protect me. If you have a basic understanding of chemistry and take the time to get to know what exactly is in Full Spectrum Crude, then this can be a very fun experimental tool to use.

I hope this is useful to you and the rest of the Future community. Disclaimer: I am no expert, I’m only a humble 24, but I love making medicine!


For Terp strip go with a medium speed and let the heat do the work.
1st pass go high speed to really smush the thicker material flat and create a thinner film for your desirables to escape.
For 2nd pass going high will get greater separation, but too high and you’ll start flinging oil around. It’s a delicate practice that takes getting to know your machine.

That’s pretty hot for decarb! Especially if you’re under vacuum. Have you noticed any loss in potency? Were any of your R&D tests done below 130C to compare? 2 hrs at 160C will push CBD and especially THC to other isotopes in my experience.