Hey Frank T, I would first like to answer you question by saying it all depends on your wash. To my knowledge there is no specific formula for knowing exactly how and when to shut down once you run into your tails. I usually run into tails at app 60% Al Vol, I am running a pot still which acts like a pressure cooker only larger. I have had runs reaching tails at app 68%-75% Al Vol. It all depends on what type of wash you are running in your still and what temps. I beleive if your running a little warmer trying to get carryover you might run into tails a little sooner than later. My best advice is color, taste and smell will change when your running into tails so keep on it. I use smaller eigth gallon jugs for destilling only becuase when I do run into my tails I will only loose a small amount of shine instead of loosing a whole quart or full gallon. The advice I am giving you is basically what has worked for me over time and hopefully will help you.

I run my tails down to about 20%. Everything collected after the drinking line is drawn I keep for the the next spirit run. Drinking line is drawn based upon your own taste & what you are using the run for. Flavored liquors made from neutrals can be a little deeper into the tails than sipping juice. I have a 5 gal glass carboy that I toss tails into, this is also the carboy I toss the entire strip run into. So on the next spirit run I am using tails from previous runs mixed in with fresh strip.