Dechlorinator
Also called: Water conditioner
A dechlorinator (water conditioner) is a product that neutralises the chlorine and chloramine in tap water, which are toxic to amphibians and to the beneficial bacteria in a cycled tank.
Because amphibians absorb water through their skin, you always dechlorinate tap water before it touches them — for tanks, water changes, and even soaking dishes. It is a small step that prevents a lot of harm.