I dont want anything huge, so I have a 26gal and a 55gal. One day I would like to test saltwater and the reefs. I would like 2 clown fish, and 1-2 yellow gobies. So now the question, how much more of operating cost would the 55 vs the 26 gallon be? And would those fish above be happy in a 26gal aquarium thats 5 sided and 24" wide?