One of these products is called Better Bait. I believe in it strongly, and my minners don't go into water without it. The biggest advantage for me using it is it neutralizes the chlorine in the city tap water. If I didn't use it, they'd be dead in 15 minutes. A pinch goes a loooooooong way
Lots of bait shops sell it, or try Grizzly Jig (mail order).