Hello,
Used both Big bud version (Liquid & Powder)
The powder is more concentrated and tend to give a little more results. Liquid is easier to deal with.
They both are their "Pros" and "Cons" if we can call that cons.
You should it from week 2 to 5 of flowering at a rate of 2.5ML/L (Bottle say 5 but i always use half ratio which give excellent results)
*If you have a longer flowering strain, you can add 1-2 week of big bud.
To answer your question, none of mine had protective seal. Just a normal seal and all came straight from Advanced nutrient factory.
If you bought it from a hydro retailer, chance he ripped you are almost negative as someone would not lose his whole reputation for a little more $$ (i know there people who do it but on an average, kind of rare)
Hope it helped you and wish you a nice day.
PS: I would suggest you to use Overdrive as well in combination with Big Bud. Both together work well!