The owner, Steve, is a great guy to deal with, and is very helpful with questions and suggestions. It is so sad that such a great product isn't in everyone's arsenal, but I've been telling anyone who will listen! I don't remember how I found them, but ordered one within 5 min of stumbling onto the site. When I got it I tested it out with a cooler of ice water and a carboy of warm water. It took less than an hour to bring it down from 90 to 60 before they reached equilibrium. Not really sure what the exact time was because I was busy on the website ordering 3 more!
Yes, the RV antifreeze is what you want. Some have different slush points. I found some at Home Depot that is suppose to go to 0* before slushing. With a ac unit glycol chiller you want to have about 15* or so difference between your set point and slushing point, so that it doesn't freeze up your ac coil. I normally run it at about 40 or so during fermentation with a hysteresis on the controller of about 15*. Then for cold crashing I bump it down to 20-25. I do that mainly for energy conservation, even though these things don't use that much power. You also lessen any undershoots that might occur with such a cold source. I ended up using vinyl tubing to run to the jacket as it was cheaper, but it does get pretty stiff at those temps. Also when running it that cold I would highly recommend tubing clamps. The connectors worked fine when I used a fridge for the reservoir, but with the super cold temps the tubing slipped off. Someday I will start a new thread with my fermentation endeavors!
