Quarantine tank size

[SaltyDog143]

In the process right now of setting up a 120gal, the plan was to find a used 15-20gal as quarantine, just wanted to confim I am on the right track. No plans of having any big fish, one spot foxface and yellow tang might be the biggest in the plan and even they will be small when purchased.

Right now I am putting the plumbing together but want to keep my eyes open for a cheap tank and stand, incase something comes up.

Thanks