Also, you can turn your 30 gallon tank on its side, if you need more floor space but you're concerned that the new tank is too large. Use the top as the front. My brother did this with a large 55g tank. He turned it on its side and put a divider in it so that he could house a young boa in each side. Stood up like a fish tank, there would not have been much floor space, but turned on its side, there was a lot!!