rat house size?

Question
Could you please tell me what size aquarium would be appropriate for 2 female pet rats? One is a good-sized pudgeball that I bought as a baby. The other, who was born missing an eye, is a little bitty thing who hasn't grown at all since I got her over a year ago (she is otherwise very healthy).

I currently have them in a long, 20 gallon tank, with a "pet condo" cage (about the dimensions of a 10-gallon fish tank plus another half...there are 2 levels and some shelves) affixed on top.

I think I have to get rid of the condo because it isn't sanitary, either for my rats or for my 2-year-old, who can't resist sticking his fingers through the bars. The rats urinate on the metal floor and side bars, and I can't seem to get it clean enough, even after running it under the shower. Also, it doesn't fit well (it was designed to set atop a 10-gallon tank, not a 20), and my rats keep escaping through the space in the wire cover I put on.

The lady at the pet store said the 20 gallon long tank isn't big enough without the condo. I want them to be comfortable.

Thank you very much for your help. Sweetheart and Caramel appreciate it too!

Sincerely, Lynne

Answer
you know what actually the 20 gal. long tank is the correct length for a rat cage. if it's height that you want you can buy a nice sized rat cage cheaper than an aquarium. I know they have a 20 gallon long small animal high rise to attach to your tank size but it's pretty expensive. http://www.delouisepetsupplies.com/prod_details.php?pcode=SWM00337&sc=5&PHPSESSI...

Considering that rats long to climb I would honestly get them a wire cage so they can climb up. If you want to buy another aquarium that has height either a 30gal or 40gal would be good for them.