I would say high flow in a qt tank if that is an option to prevent spread to other corals. As for melafix i have used it twice. Dosed directly into tank when i had a bad brown jelly issue. Turned off skimmer for 24 hours....big water change... skimmer on 24 hours....repeated for about 12 days. I had no negative impacts to my mixed reef tank (sps,lps,zoa,softies) Thankfully it saved all my torches and frogspawn and the majority of over 100 ricordea which all had a bacteria issue. Now melafix is part of my dip process for some types of coral.