How and why I use Epsom salt:
Why-to treat symptoms of constipation, bloat, edema or swelling from injuries, swim bladder issues.
Epsom salt also has antibacterial/fungal properties just like aquarium salt that can be helpful when symptoms are caught early and treated
How I use it, Epsom salt 1tsp/gal up to 3tsp/gal for 10 days max
Anytime I am treating a fish I place them in a small QT container so that I can make 100% water changes, if not in small QT I make 50% daily water changes.
I like to treat in QT so that I can pre-mix the Epsom salt or aquarium salt so to give the correct dosage.
It is important to treat with correct dosage so not to cause bad side effect, both over and under treatment can cause problems.
Long term use of either Epsom salt or aquarium salt can be hard on the fish and can create resistant pathogens/parasites.
Often you will see bloat for no reason in a fish that aquarium salt has been used long term with some species of fish, this is most likely from kidney damage from the long term salt use.
Epsom salt is plant safe and aquarium salt can be harmful to some plants when used long term, some species of fish are really sensitive to aquarium salt and should never be used as a treatment or long term for that matter.
The Epsom salt that you have is fine and what I use.