24' round - 13,200 gal => 9

Hi, I'm a first time user of the Intex SWG system. I'm trying to adjust the salt level. The size of the pool is 24'x54" round, the text strip that I used was AquaCheck7 the results were

Free chlorine 3
T chlorine 3
Stabilizer 50

Alkalinity 120
Hardness 250

Could you please help me with this problem, I've drain the pool twice but I guess not enough.

Please help, thank you.