Try driving it up to 84 for a week or so... I would not use any additives in the main tank no matter if it says it is safe or not. If it says it is, and it truely isn't, Then there is a very long turn around time to get the tank back in order. If it is ICH that you are fighting, Try the 84* and maybe a quick FW
dip in RO
water with a small amount of tank water to just give a hint of SW
. Let the fich stay in no more than 15 min and you have to never leave their side, it will go crazy at first but then settle down. Watch close because this is when you cannot leave,, just watch and watch and if it gets ancy, go ahead and put it back in the tank. I know it sounds harsh, but it works. I have had two fish now live well afterwards and no ICH. Now if they have something else, I would treat them in the QT again and use the water from the main tank to fill it. Then treat with the product you are talking about using. This will ensure that you do not poison the main tank...
Addition, the Garlic is good, and I do use a UV
light 24X7. I have not had the first outbreak since I started keeping my tanks at 82 - 84*. I don't use Garlic, and I dont use Copper anymore because I could not get it to work.. I believe in the upper temps and FW
dips. Works for me