HCL is Muriatic Acid or Hydrochloric Acid. I'm adding in order to raise my CYA level and also bring my PH and TA down.

I decided not to wait another day for the kit (and hope it actually arrives as estimated), so I added another gallon of Muriatic Acid and later shocked with 10 gallons of liquid chlorine. Hoping for better results with the extra gallons of chlorine.

I will definitely provide better readings when the Taylor test kit arrives. Thank you!