Spa Choice 472-3-3041 Re-Energize Oxidizing Spa Shock Chemical, 2-Pound

Has anyone weighed the bottles when received? Lots of complaints about 1/2 empty bottles. Sold by weight.

Why doesn't it say shock on the bottle ?

I read everywhere to "shock once per week"... Why does this bottle say "after every use" ?

My container came 3/4th filled and without a seal. Should there be a seal?