I think we need to go a step back here. First thing you need is a proper test kit:
Test Kits Compared. We generally recommend the TF-Pro.
Until your kit arrives keep adding 3ppm worth of liquid chlorine per day. Once you have your kit, run all the tests from the kit and post the results in the form
FC
CC
pH
CYA
TA
CH
Water temperature
Then we take it from there.
WIthout a known CYA you won't know the correct SLAM level . And without the FAS/DPD chlorine test that is in the recommended test kits you will not be able to accurately test FC at the required levels.
Have you ever used Trichlor or Dichlor to add chlorine? Those two increase CYA levels. Calcium Hypochlorite and liquid chlorine don't. But Cal Hypo increases calcium levels which can lead to scaling eventually. That's why we recommend to only chlorinate with liquid chlorine or a salt water chlorine generator. A SLAM should be done with liquid chlorine, SWG turned off.
CYA is best added on its own to a defined level.