Filtration is extremely important for proper axolotl care. Most breeders recommend sponge filters because they are relatively inexpensive and have a low flow. Some axolotls can be stressed by too much flow. However, the more filtration, the better because of the high bio load. These guys can be pretty messy!
The staff at Lizzy's has had GREAT luck with the fluval canister filters. So much so that we have one fluval canister filter for each of our main tanks. This filter sits outside the tank giving your amphibifriends more room. The flow rate can very easily be controlled with just the movement of a single lever. They are extremely efficient and we have no regrets about the investment.