WOW!! What hasn't been added to this pool. I'm sorry to say that you have been "pool-stored" as we call it around here.

Do you have a test kit? Post a complete set of current water testing readings. Your most critical issue here is your low pH. Any reading below 7.0 is acidic and can damage the pool. Continue adding Borax a box at a time slowly to the skimmer while the pump is running. Wait a couple of hours and then retest pH and redose as needed until you get the pH above 7.0. Once the pH starts to move, go to 1/2 box doses.

Turn off the chlorinator and remove the floater and the tab in the skimmer. Trichlor pucks are doing two things to your water. They are very acidic and are driving your pH down and they are also adding more CYA which you do NOT want. If your CYA (stabilizer) is testing at 100, that means it could actually be even higher than that since test kits can't differentiate over 100.

Quit taking advice from the pool store. They are not helping. Throwing a bunch of pool store products typically just make things worse.

Did you fill this pool from a well?

Post again with requested info and answers to the questions and then somebody here can try and help. Welcome to the Pool Forum!