I am a science teacher at Nathan Hale High School in Seattle and have about $700 to create a temperate marine aquarium in my classroom. I am looking for recommendations. I am especially interested in methods to chill the water. Can I use a small refridgerator to cool the water if I get a 50 gallon tank? How about a 90 gallon tank? Filtration methods? Any recommendations on good books to lead me in the right direction?