Routine hot tub treatment depends on maintaining sanitiser. For UK domestic spas and smaller commercial sites, Zagosa Industrial offers four Zagosa Spa & Pool systems: stabilised chlorine, bromine, BCDMH and chlorine dioxide.
A stockist's view of the three sanitiser chemistries: where each sells, how it behaves in heated water and what it costs the end user to run.
| What matters | Chlorine | Bromine | Chlorine dioxide |
|---|---|---|---|
| Typical use | Routine daily sanitising at the lowest cost | Spas where a gentler, more stable residual is preferred | Clean-up treatments, biofilm removal and recovering poor water |
| Working level | Free chlorine 3 to 5 ppm | Total bromine 4 to 6 ppm | Applied as a periodic clean-up dose rather than a maintained residual |
| Behaviour in heated water | Depletes more quickly at spa temperatures | Holds its efficacy in warm water | Strong oxidiser; the usual choice where biofilm is suspected |
| Dependence on pH | Most effective between pH 7.2 and 7.6 | Tolerates a broader pH window | Performance changes little with pH |
| Smell | Chloramine odour develops if combined chlorine is not oxidised | Less pronounced than chlorine | Little odour at recommended doses |
| Running cost for the end user | Cheapest per week | A little above chlorine | Higher per dose, offset by infrequent use |
| Zagosa Spa & Pool lines | SDIC granules and 20g mini tablets | 20g bromine tablets and BCDMH granules | ChloroKlean chlorine dioxide |