Dear Godfsihgirl 1999,
With frequent water changes that's been treated with Prime, a week is doable and the fantails will be thrilled with the larger aquarium and filter. So hang in there, your fish need you.
Yes it takes out the clorine. It may even neutralize the amonia etc. But when you need to replace the one you have get Prime, it's super and in an emergency you can add 3-5 times as much to help with spikes.