wow.. you really are close minded.. you found what info you wanted to find..
there are several anti caking agents that can be used for salt.. Sodium ferrocyanide (as an example) will break down in sunlight to cyanide.. certainly harmful to fish.. many contain copper, that can be bad for plants.. some may be ok.. but again, why take the chance? use pure salt and avoid the risk, that's not trying to scare anyone, it's presenting facts...
good luck with your garden uf
fertilizers in the garden are a great thing.. but when there are fish in the mix (you seem to ignore that fact in many of your discussions) the equations change..
oh, and i'm not a "hippy", but name calling always helps an me win an argument too!