Medium Tanks (31-100gal)

so i am limited with space in current house and its rented etc but you no how it goes ,,,,,you get a tank and yep your truly bitten by the bug , then the words we have all heard ring through our heads shouts out UPGRADE . the story so far has gone from a 24 d&d to my current rio 125 , now i love this little tank but was still not happy , but hold on i cant go more than 80cm in length as i wouldnt like a tank overlapping over the windows mmmmmmmmmmmm what do i do ? aint really got the money...