'I would be gutted if I lost my blue faced angel due to anything a QT could've prevented ' - that is EXACTLY the point.
How big it is totally down to personal preference, and what you're going to QT. If it's little clowns and so on, 10's are fine, if you have an expensive taste for large sohal tangs then a 55 is what you would use. You might blanche at using a 55 for QT, but if you're QT'ing hundred dollar plus fish then the cost of a second hand 55 is negligible.
Bear in mind this doesn't have to be fancy. When I was breeding a lot of freshwater fish my grow out tanks were 40 gallon plastic boxes from IKEA. Also bear in mind that when you're not using it, break it down and put it in the garage. This is to be advised anyway else it will invariably end up as a second display.
Whether you QT the single fish that goes in a nano is a good point. However if, or an invert dies in there you are going to know about it, and if it dies in your nano form ich where you can't treat it, then I wouldn't put another fish in for two months |