How can I use my crock pot for a stove top soup?
It depends on what kind of settings your crock pot has. A low simmer on the stove is probably equivalent to something fairly low on your slow cooker, though. If all you have is warm, low, and high, you want low - in some cases it might be too hot, though. You're aiming for just short of boiling, so a setting that gets you a few bubbles now and then is good. More than that and you're cooking a bit vigorously, and on a "warm" setting you likely aren't heating it enough to cook properly and stay safe. If you have some kind of continuous settings, you can possibly adjust to get exactly where you want!