Couldnt agree more with Leewink, however dont write off disneys Epcot centre, they have a 6 million gallon tank, they call it a reef but corals dont look real to me. they have a visitors section as well. you can even pay an “extra” 100 or so quid and spend 4 hours in the research centre with the staff and dive in the tank. didnt do that – couldnt quite justify it, but next time maybe.
Also in the uk, try the rainforest cafe, if its the same as florida (i think they are ALL the same layout) then their tanks are pretty impressive as well, tried to see their filter section in Florida but again high secrecy, every one pleaded ignorent.
But again yes Seaworld IMHO the most importnt place to visit if you go to Florida, I’ve been 3 years running now.