we really should Q for a month, especially wiht ick, which will live almost that long, and most lfs will not hold a fish for 30 days, and even if they did, who's to say that they did not get anything in the day befor you pick up the fish that got on or in your fish, right before you bring it home, thi sis one of those cases wher it is much better to be safe than sorry
and i would definitely have a seperate pump and water system all toghether(if you get ick in your quarentine, it is in the whole water column)