- probably not a decarb issue issue. I would recommend starting here
- I don’t understand “losing potency”. That implies starting with 90% and ending with 75%, which I don’t believe is what you’re trying to convey. At a guess you’re saying that “I’ve run almost the same method multiple times, and I’ve tested at 90% THC in the past, but recently the output has been testing lower”. if your etoh crude is well made, you should be in the 65% THC range going into SPD. 65%=>75% is gaining potency, even if it’s not the gain you’re used to.
The standard answer is “show us a picture” ie: what does the chromatogram look like? Isomerization or degradation is the first place to look. low vacuum is often the primary cause. although acid activated carbon in the boiling flask has also taken some blame.
- how does one decarb in 10:1 ethanol? with a BP of ~78C I would expect the solvent to leave before much decarb happend. I find that recovering 15gal of tincture at 78C over 12hrs does lead to complete decarb…but recovering 5 gal in 4hrs does not.