There are several alternatives to ca rxtor.
(0, ca rxtor)
1, kalkwassor
2, kalk reactor
3, two part calcium additives
4, snake oil/dust/dirt
Depends on your budget and time, 1-3 are all good options. Options 4 is for people without budget and time constraints.
The following is a short term ranking of cost (purchase $)
4<3<1<2<0
The following is a long term ranking of cost ($)
2 ~ 0 < 3 ~1 < 4
The following is time for setup (hour)
4<3<1<2<0
The following is time for keeping the routine running (hour)
0 ~ 2 < 1 < 3 ~ 4
Hope this helps.