I'm not familiar with conditioning salt. Also, 90% of LFS (local fish store) employees don't know squat about fish except for what they read, and that's minimal, meaning they have no real experience. And as far as I know, petco is of the worst. also I have yet to meet a fish wise LFS employee.
I'm sorry I don't know much of the peeling. maybe you used to much treatment, maybe it just wasn't good to begin with. But IMHO you should've done a progressive salt treatment for your ick problems, or uped the temp to 86degrees, or both cause that's a tried true methods to get rod of ick.
in the salt treatment , you add a teaspoon of salt per 5-10 gallons of water. Do a 50% water Change mixing in the salt with new water. And repeat in a few days. When it comes to salt I've only hears of aquarium salt and Morton's all natural sea salt being used.
do they still have ich?
did you cycle the tank?
do you know what cycling is?( don't be upset if you don't because I didn't till a couple weeks ago, and LFS employees never told me anything about cycling either)
I think that's about it.