I got two problems with stock cooling down in sinks with running water:
-The first is that your pail/bucket bobs up and down with the water current and eventually tips over, spilling your contents in the water.
-The second is that your pail/bucket bobs up and down and "goes with flow" traveling right under the stream of water from the faucet, diluting and ruining your work.
In both cases you can shove a sheet pan across the corners of the sink to keep the bucket from moving, but this defeats the whole purpose, as the water trapped between the bucket, sink walls, and sheet pan can't move and do it's job properly.
Ice in the water bath works best, but in the best interests of keeping peace with the bar people and the kitchen, it's not a good idea to raid the ice machine. As before, I strongly suggest using the 4 ltr (1 us gallon) milk jugs: Wash them, fill 'em up and freeze them. Lob one or two frozen jugs in the water bath, and you're golden. The frozen jugs make pretty good ice wands too, if mngmt is to cheap to buy the real thing. One place I worked at we would make our own "ice logs", we'd just fill those 4-bin plastic cutlery trays with water and freeze them. We'd pop them out of the trays and keep them in an old picnic cooler in the freezer, and lob them in water bath as needed.