Pesky buildup and stains are no match for nature's enzymes. This class of chemicals digest the food you eat and liquify organic material to keep the environment clean.
Sodium Sesquicarbonate (mineral-based water softener), Enzymatic Blend (drain maintainer).
For free-flowing drains: Dilute two teaspoons in a separate container with a cup of warm water. Make sure product has dissolved completely. Pour liquid down drain. Follow with two cups of water. Leave in for a minimum of an hour; will continue to work up to 24 hours.