Campden Tablets (Potassium Metabisulfite) - 25 pk
$1.99
In wine, used to kill naturally occurring microorganisms and prevent spoilage. Also works as an antioxidant. Add at a rate of 1 tab/gallon to achieve 75 ppm free SO2.
Can also be added to water to remove chloramine (1 tab is sufficient for roughly 5-20 gallons)