It's sadly below freezing in my environment so a garage setup is probably not an option it's unfortunate because from what I've read formaline works wonders and is one of the only effective treatments for brook. Deciding to risk my family of cancer for a few fish or try my luck without it. Oh the decisions.I have also had reservations about using formalin in the house. I’ve set up a hospital tank in the garage the past before to work around this. Not sure if this advice works for your case.