A water flosser does nothing against calculus. I use one myself and itβs a nice feeling but for calculus you need real floss picks and brute force.
No you can scratch it off with those metal base brush sticks that you stick through the openings between your teeth. Itβs not perfect but if you do it regularly it helps A LOT. The dentist will have to clean up the trickier parts though (like the inside/back surfaces).
I find it more efficient, I'm getting stuff from between my teeth which I can't get out with a regular floss pick.