Sounds to me like he is COOKING these chicks.  Using a 250W heatbulb over a small brooder like that.  I had a 250W, I had to hang it almost 3ft above the floor of the brooder, so it would not get too hot.   I bet the chick was gasping for breath.  Get a THERMOMETER man,  And see where the temp is.  And stop with the aditives to the water.  Just fresh cool, NOT cold, water everyday. And did I read it right, You have/had 18 chicks in that small rubbermade container.  I bought 18 chicks this spring, I had them in a brooder I built that measured out at  4X5 FOOT, And that was looking kinda small when I took them out and moved them to the big house.  Once you get your temp. under control, you better start building a new and BIGGER brooder.
Jack