How much salt, add to tap water to purge bivalvia? I live Toronto, and our tap water is fresh water, not salty. I talk for each LB of bivalvia like clams mussels. 


How much tap water? 
How much salt to add?
What g of salt per LB NEVER to outstrip? What concentration kills them?


For pics, pls see After purge mussels 6 time in salt water 20 mins each, why they still exude much grime?
If you want to simulate seawater, you need 35g per 965g (more or less 1 liter)  of fresh water.