Robert,
I used Gulp fish fry a lot last hard water season and the juice in the little jars, I found would turn to slush and would not affect it's effectiveness..... I also found that it turns to slush faster if the lid is left open. I usually carry those jars in my big white pale so that it's not left directly on top of the ice.
Once I use the last piece in the jar, I keep the juice for refilling other.... the lids do leak a little so I recommend not carrying the jars in your coat pockets
Jacques