< < Salty Ice Rink
A Salty Ice Rink
While the rink may look like one big block, it’s actually made up of billions and billions of tiny bits called molecules. You are made of about a billion, billion, billion of them. They’re always bumping around with heat, but as they get colder, they can slow down and stick together. That’s how ice freezes; the molecules slow down enough to make a crystal, rather like putting LEGOs together. You have to slow them down to stick them together.
Imagine you built a tower out of LEGOs, and someone came by and switched a few LEGOs with K-NEX. What would happen to your tower? It would fall! Now imagine you traded more and more LEGOs for K-NEX. Eventually, you would have a K-NEX tower that would stand just fine!
Has your driveway or sidewalk ever gotten too icy? How did you melt the ice? With salt!
The salt bits get in between the water bits, like K-NEX in between LEGOs, and break up the ice, turning it into salt-water. It seems funny, but they freeze the ice skating rink the same way you melt the ice on your driveway or sidewalk. Those tubes under the ice need to get really cold, without freezing inside.
Try it! 
Melt ice online. Play with the blue box in the middle of the page.
Some rinks add ordinary salt to the water in the tubes to keep them from freezing. Most modern rinks, including the BlueCross RiverRink, now add Ethylene Glycol, the same antifreeze you put in your car.
Neither the rink nor your car uses pure antifreeze. You wouldn’t pour too much salt on your driveway, or you’d have a driveway full of solid salt. If you use pure antifreeze, it can actually freeze sooner, at a higher temperature. The rink uses 60% Anti-freeze and 40% water. Cars work best with 50% and 50% so that the liquid won’t boil in your hot engine either.
So how do they make the ice? Click for more.