So, you, by yourself will be caring for all of these tanks? But you also have a full time job and tanks of your own? How exactly do you plan on fitting all of this in to your personal life? All of the large fish you are wanting require very specific diets and need to be fed daily. You are literally talking about a full time job caring for these guys unless you trust anyone at the school enough to properly feed, check water parameters, and daily monitor these guys.
And, as others have said, 100 gals of water change on a 600 gallon tank is nothing. Thats roughly a 16/17% water change, that isn't enough even for the second stock list you released. My 220 is lightly stocked with a 55 gal MB sump and I still change 80-85% of the total tank volume every week. Even with a drip system, I feel like you will be battling nitrates unless you are dripping 100 gallons a day.
I understand the want for all the different types of aquatic animals, but I can't help but thing a 1500-2000 gallon freshwater tank with all the monsters you are wanting would be easier, cleaner, and look way better than a hodge podge of random crap on a wall in a school.
