I agree about the soap, also try to purchase test kits, because like that you can go by something other than a LFS person telling you a vague answer like "your water is fine"
i had my minnows in a jar, which was a ecosystem that provided the essentials and basics to them for the 10 days. than i opened the jar, after the ten days and put the fish into a new jar that was clean and everything, temporayliy, until i found them a tank. And then after a couple day i moved them into the tank, after it had settled. also, i had made sure that both jars, provided the fish enough room to swim freely.
that by using biodegradable soap it'll help clear up the white residue from that was previously there.