Not to be confused with sodium bicarbonate (bicarb), sodium carbonate is also known as washing soda or soda cyrstals.  It's a water softener and sink/drain cleaner in an eco-friendly home.
 
Try it for - 
 
Laundry: add a tablespoon to your detergent drawer along with 2 tbsp/a laundry capful of castille soap or Fill laundry detergent.