Looking to upgrade

[Mash_01]

I am looking to get a bigger tank for my Axolotl, Mash, who is somewhere between 8 and 10 inches long.
I currently have her in a 20 gallon tank, but I am looking to get her something bigger.
What do you all think would be the ideal tank size for an axolotl of her size?
She is not very active, though she has a strong feeding response, if that factors into ideal tank size.

 

[wolfen]

for her size right now ie.. 10" 20 gallon is a minimum, for additional growth 30 gallon plus would be needed.