Rach Events' foam machine was a tremendous enhancement to a rooftop pool party I had organized. They were professional, on time, and provided great service. It took them about 15-20 minutes to set up, and the fun lasted for almost 4 hours. The foam isn't a constant stream, but rather the way they do it is strategic and brilliant - similar to a DJ. They feed of the audience, and shoot out foam when the party seems about to get going, is already going, or keeping the party going in long enough time spans so that it doesn't lose the "wow" effect.
Enjoy, and definitely worth the money! Fun for kids and adults! I promise!!