That's about 100 litres, I think. That should be a fine size for up to three or four axolotls. They prefer a pH of 7- this is neutral. Otherwise you may get problems with peeling skin, etc. It is possible to get products that remove chlorine and chloramines, and also products to bring the pH of your water up to neutral. Remember,. if you choose to introduce other axolotls later, you must quarantine them for quite some time.