Silver and copper mineral cartridges reduce sanitiser use, but reduce is not the same as replace. Here is what they do, and what they do not.
Mineral cartridges (typically silver and copper) cut sanitiser demand by up to half and improve the feel of the water. They do not, however, replace chlorine or bromine. Every reputable manufacturer pairs the cartridge with a low residual of conventional sanitiser. Anyone telling you otherwise is selling something.
Silver ions kill bacteria slowly and reliably across a wide temperature range. They do not oxidise organic matter, which is the other half of what a sanitiser must do.
Copper inhibits algae and adds some bacteriostatic effect. It is the reason mineral-cartridge tubs rarely go green even between heavy uses.
Neither responds to spikes in load. A garden party with eight bathers will outpace the cartridge before lunch is finished.
Maintain a low residual of free chlorine (around 0.5 ppm) or bromine (around 1 ppm). The minerals handle the slow, baseline kill. The traditional sanitiser handles the spikes and the oxidation.
Shock weekly with a non-chlorine oxidiser. Without it, organic matter accumulates and the cartridge slowly loses effectiveness.
Replace the cartridge per the manufacturer's schedule. They are not magic. Once depleted, they release nothing, and you will only know because your sanitiser demand quietly doubles.
Sensitive skin households. Half the chemical residual means half the dryness and half the odour.
Lightly used family tubs. The slow, steady release matches an unused tub better than the on-demand dosing of pure chlorine or bromine.
Hard-water areas. The minerals help inhibit scale formation by competing for surface adsorption sites, which is a small but real bonus.
Yes. The combination is gentle and stable. Use the cartridge alongside a 1 ppm bromine residual.
Only if you let copper levels climb. Test copper at every refill if you have a mineral cartridge in soft-water postcodes.