First thing to do is to find out zackly WHAT is leaking.. You describe a leaking hose pretty good.. If the tank only has a small space that is leaking I would consider glassing the spot..
If you just MUST have another tank look around for a good used plastic one of the same size.
To go to a larger tank requires a different guard/pan underneath the tank...they are not the same. You will also need a different pump/semder in the larger one.
Big Jim <img src="/forums/images/graemlins/pfft.gif" alt="" />

professional bovine relocation specialist