In my opinion, tortoises...any specie of tortoise...should be set up outside. A nice, safe outdoor pen is the best place to keep a tortoise. When weather doesn't permit, then a stock tank (the largest you can affort) would be a good second choice, but first choice should always be outdoors.
How long and wide are those tanks? I have a tortoise table I built out of a bookshelf, its six feet long and three feet wide. My adult Russian female lives in there and seems perfectly happy. She also has a new outdoor area that is about ten feet by eight feet on our patio, and a zoo med tortoise run for putting her around the yard in. In Wisconsin there's only a few months of summer weather to take her out though. I wouldn't want a table smaller than the one I have, she explores every corner of that thing.
fish tanks generally dont make good enclosures, they are too tall and torts dont understand what glass is, if they can see through it they will just sit there for hours trying to walk through it. look for an old bookcase to make a cheap tort table. even a small kiddy pool would work for a smaller species like Testudo.