Dude listen, honestly, your tank is hosed. Nothing you can do will fix this. What LFS was this?
You have no other option than to throw out EVERYTHING and start over. I wouldnt even trust the tank itself anymore.
I guess ill tell you this again, you need to research everything on the internet. You will get a much better answer than asking some $12 an hour Fish Store employee that just wants to sell you stuff.
Dont even bother with all this polypad, counter chemical BS. Just toss everything and start over.