Star San is an acid based sanitizer from Five Star. It is quick, odorless, tasteless and safe for most materials (except for softer metals). Use 1 oz of Star San per 5 gallons of water, it only takes 1 minute of required contact time to sanitize. This makes Star San very economical and convenient.
Star San creates foam when in action. This foaming insures coverage and contact time in larger vessels to better penetrate into the nooks and crannys. Any foam that is left behind in your carboy or keg will not harm your beer or you. This is a no rinse sanitizer that is perfectly safe and non-toxic, nor will it impart any flavours or odors.
Do not fear the foam!