Firstly i am UK based and have a spa made over here so not a brand you would know, Its by Blue Whale Spa.
At present i use Chlorine Granules as needed by my test strips and normally a bit of PH+ now and then.
I shock it once a week with Non-Chlorine Shock and change the filters weekly
I do struggle to get more than 3 months out of it before i change the water i it is very dirty.
We always shower in PH neutral stuff before every use.