Stubhoy67

Hi everyone, new hot tub owner here! im struggling with the stabilizer in my new Canadian spa hot tub. My ph is 7.2, chlorine 3ppm and total alkalinity Is 80 bit my stabilizer is 300 ppm. When I add chlorine next day I test and chlorine all gone so I’m wondering if it’s to do with the stabilizer. I half emptied my hot tub today and refilled, sorted my ph and chlorine and stabilizer is still at 300ppm. What am I doing wrong? The water is crystal clear.