Spa Salt Water Sanitising, Is It Really Chemical Free?

15 May, 2021

Can I sanitise my spa with salt?

(Information by a well respected NZ spa pool retailer who’s been in the industry for more than 35 years and sold all methods of spa pool sanitisation available in the spa market)

A salt water spa pool seems a great concept and is marketed aggressively as an alternative to using “chemicals” but has a host of issues that need to be explained.


The salt is broken down into chlorine


Expensive replacement of salt cell up to 3 times per year @ NZ$800

Any salt swimming pool or spa pool needs an electrically operated cell where the salt  in  the  water  is converted to chlorine. One of the major reasons we no longer sell salt water spa pools is that the salt cell in these spa pools has been extremely  unreliable.  As a result, we have had many customers extremely dissatisfied with the short life of the cell and the replacement cost (RRP NZ$800 just for the cell – fitting is extra). The warranty on these salt cells is only one year. We have had some customers who have had up to 3 cells replaced in a year!  Although  these  were  initially  done  under  warranty,  once  that  warranty  expires, there’s  no  comeback.  We have been left with justifiably unsatisfied customers and the importer of these spas unwilling to assist us in making these problems right.


Salt chlorinator needs manual adjustment by you, the owner

Unlike a swimming pool salt chlorinator, there is no feedback mechanism on a spa pool salt chlorinator. This means you have to manually turn up or down the amount of chlorine you require in your spa. All good if you are a regular user with the same frequency. But if you forget to turn it down and don’t use the spa pool, the levels of chlorine just keep going up.


Salt chlorinating can damage jets, plumbing, headrests & spa cover

High levels of chlorine in warm water can cause oxidation damage to the jets, plumbing, headrests and underside of the cover. On the other hand if you suddenly have friends around or a party of kids and all use the spa, there would insufficient levels of chlorine to maintain sanitised water and you’d have to remember to manually add some (it takes 24 hours to complete a boost cycle and create additional levels of chlorine)

Salt levels although low, are sufficient to cause rusting and corrosion of metal componentry in the spa (and the  surrounding  area  –  the  owner  manual  recommends  washing  the  area  around  the  spa  to  remove  salt build  up  from  splashing).  When  these  salt  cells  were  introduced  into  New  Zealand,  the  salt  level concentration  in  the  water  was  set  at  750  parts  per  million  (ppm).  This  level  was  chosen  to  reduce  the effects of salt on the spa components (heater, circulation pump, jets etc). Because the salt cell life became an issue the recommended salt level was raised to 1500 ppm. That still hasn’t solved the problems with cells consistently lasting less than 18 months. The recommended salt level is now 1700 ppm, almost two and a half times the level initially used and recommended as preventing damage to the component

It appears that even with this higher salt level, cell life is still a major issue. Overall the running cost of the salt  water  sanitising  cell  system  can  be  as  high  as  $10-12.00  per  week  for  the  cell  alone  (based on an 18 month life and RRP of at least $800 + fitting). There  is  an  additional  cost  of  the  balancing  chemicals  and Nature 2 which is now recommended in conjunction with the salt chlorine system. This can bring the weekly  cost to over $15.00 before  power  consumption  is  calculated,  making  the  claims  as  ‘the  cheapest  lifetime ownership’  extremely  hard  to  prove.  You  also  still  need  to  balance  your  water  and  maintain  correct  pH (through use of chemicals)