You would be amazed at the technology, time and effort it takes to maintain a sheet of ice. This link from the How Stuff Works website shows how a rink is built and how the ice is made. The Hagerstown Ice and Sports Complex is a sand based NHL size rink. It takes over 10,600 gallons of water to build an ice sheet when the ice is taken completely out. Due to the high traffic at the Hagerstown rink, the ice thickness is between 1" and 1 1/2" thick due to usage. The ice is held at a temperature of between 22 and 25 degrees year round.