Star San is an acid based sanitizer that is quick, odorless, tasteless, and safe for most materials except softer metals. As a high foamer, it’s foaming action ensures coverage and contact time in larger vessels and better penetration into nooks and crannys. Any foam that is left over in your carboy or keg will not harm your beer or you. If you plan on making some up for spray application, it is best to use distilled or RO water to maximize the life of the unused portion (minerals in tap water reduce the shelf life of Star San once in solution). If a lower foaming alternative is preferred, for bottling or multiple batches, check out Saniclean.