Well if it is coming from tap I would suggest getting something like seachems prime to use during water changes to temporarily detoxify ammonia and nitrites. Have you tested for nitrites yet? And if you get a baby axolotl you can keep it in a small container and switch it back and forth everyday 100% water changes. Which is what I would suggest anyways for one so small since its easier to feed them this way. This is how I do it.
I have kept axolotls for a while. I can try to help you out if you have any other questions. I love these creatures! They are so full of personality.
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