Non-chlorine shock is a powerful oxidizing agent. It kills bacteria and eliminates residues left behind by bathers: sweat, sunscreen and so on.
It is compatible with all filtration equipment, and suitable for all waters, even very hard.
Shock treatments are essential for maintaining clean water in your hot tub. You should shock the water once a week or whenever the bromine level drops to zero. For heavily-used hot tubs (including any commercially-operated spa), add shock at the end of each day.
The big advantage of non-chlorine shock is that you can add just one or two scoops then use the spa 5 minutes later.