If your fishing the same place all weekend (lake, pond, river) and you could trust them not to be tampered with, I may think of hiding them somewhere nearby (in the water) in one of those metal minnow buckets with a big rock on top. Don't overcrowd them (it causes a lot more stress on them)...use two buckets if you have to. Phil is right for storing them at the house...keep them as cool as possible. Don't use your tap water if it has chemicals (chlorine) in it. If you want to make a minor investment, buy one of those big 5 gallon-type minnow buckets with the aerator built in. they work well...but no matter what..keep them cold. Put some ice around the bucket but not in it, again, if the ice contains tap water chemicals

Chuck7,

The problem you may have had was that that water, especially if it is constantly recycled and there is significant plant and leaf debris, may have had it's PH way out of whack.