The embodiments herein relate to a sheet production apparatus. A vessel is configured to hold a melt of a material and a cooling plate is disposed proximate the melt. This cooling plate configured to form a sheet of the material on the melt. A pump is used. In one instance, this pump includes a gas source and a conduit in fluid communication with the gas source. In another instance, this pump injects a gas into a melt. The gas can raise the melt or provide momentum to the melt.