Silver passport question

[spr0m]

We bought silver passports for BG williamsburg this fall and in the perks listed it shows a 50% discount for SeaWorld and the other parks AB owns. Has any used this perk before. I guessing we have to bring our passports with us to get the discount. Do we just show them at the ticket window at the park or do we need to advance purchase the tickets. If I can get into SW for 1/2 price than we'll take the kids for sure but I can't see myself spending over $100 for one day and would just stay at WDW instead.

Thanks in advance