cool, Great thread. I love learning off other cheap fish nerds like myself. I spend so much I trey to save where i can
Epsom salt also have beneficial trace elements. I use these on my african cichlids.
Epsom salts is MgSO4 and yes you can add it as a water hardener/GH booster/plant fertilizer. Plaster of Paris is CaSO4 and can also beused as above. Stump remover is KNO3, some enemas contain phosphates, baking soda is a KH booster... There are all types of products you can get to avoid the aquarium markup.
Fish need .3-.5% for healing.
And when I say 1 cup, I mean measured.
A 240, would get 2.5 cups to heal at .3%
Electronic saltinity meter..
But for my koi I don't measure.. I've been doing it so long, I just eyeball it.