all but three fish dead this morning

I can't see the electrical issue being there since the stinging feeling persists even after removing my hand from the water. After the baking soda/epsom salt mix last night, this morning the issue is not there anymore. I am thinking for some reason the water turned into some sort of acid or base. As of now my ph is about 8-8.2 I don't recall my alk reading though. As previously posted I am going to switch out all my water this weekend and go to a sand base. Basically the tank is going to cycle again is my thinking.
 
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