It is in their nature to Waller in any kind of water it doesn't matter a children's pool is perfect.
They can be in any water even if a puddle in the yard or in ur tub whatever works for u
I use kid pools and the love it, just need to dump it when water gets dirty
I am not sure myself I would try tap water if they start to get an issue I would change to bottle water if they get an issue or it doesn't clear up I don't know what I would do unless you have a pond available to you to use
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