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Ionisers have been the subject of three previous Technical Information Bulletins(1-3) and, despite Bio-Lab's reservations on their bacterial efficacy and their potential for staining, systems like Nature2® and Questa® continue to sell in significant numbers. Part of this is driven by pool builders, who install ionisers at the time of pool or spa construction. As some BioGuard dealers sell these units, and many more have customers on their database that use ionisation as their principal form of sanitation, it is appropriate to indicate which products are compatible with ionisers and which are not.

To determine compatibility, recall that most ionisers generate either copper alone or copper and silver ions. The one exception is the Nature2® spa unit, which generates copper and zinc ions. In a nutshell, all BioGuard and SpaGuard products are compatible with ionisers - including the entire range of chlorinating compounds - with the following two exceptions:

Product SpaGuard Brominating Tablets
Constituent Bromochlorodimethylhydantoin (BCDMH)
Staining Risk Moderate
Reaction with Copper As hypobromous acid and hypobromite from the BCDMH are broken down,
one product is bromide (often referred to as "spent bromine"). This forms
copper(II) bromide, a black compound that is very soluble in water at
25ºC.(4) There is no effect on efficacy and no increased staining potential.
Reaction with Silver The bromide forms silver(I) bromide, a cream-coloured compound that is
insoluble in water at 25ºC.(4) This renders the silver ineffective against
bacteria and can result in staining.
Reaction with Zinc The bromide forms zinc(II) bromide, a colourless compound that is very
soluble in water at 25ºC.4 There is no effect on efficacy and no increased
staining potential.
Product
SpaGuard Brominating Concentrate
Constituents Sodium dichloroisocyanurate, sodium bromide
Staining Risk Moderate
Reaction with Copper Bromide is again present, so reactivity as for Brominating Tablets.
Reaction with Silver Bromide is again present, so reactivity as for Brominating Tablets.
Reaction with Zinc Bromide is again present, so reactivity as for Brominating Tablets.


Initially, it was believed that SpaGuard Perfect Balance might cause problems, as the phosphate salts of copper(II), silver(I) and zinc are either sparingly soluble or insoluble at 25ºC.(4) However, the Technology & Development group at Bio-Lab US reports that, at the time of writing, there have been no reports of staining or other negative effects. Likewise, silver can combine with tetraborate or boric acid to form a sparingly soluble white compound,(4) but again tests have shown this to have a low risk of staining. As such, products like Power Chlor, Pacific Blue Power Tabs, Burn Out Extreme, Lite, Optimiser and Optimiser Plus are all acceptable for use with ionisers. Whilst Bio-Lab no longer markets Soft Swim in Australia or New Zealand, it should be added that biguanide (eg. Baquacil) is not compatible with ionisers, as the copper and silver combine with the species to form insoluble compounds that will discolour water or result in surface staining.

The manufacturer of the Nature2® system advises that the unit is incompatible with copper algaecides. This appears more to be insurance against pool operators complaining that staining originated from the device than any real incompatibility issue. Indeed, it is Bio-Lab's contention that the use of MSA II, Back-Up II or Protector would be beneficial because the excess anti-staining agent in these algaecides will combine with free copper from the ioniser and, hence, lower the risk of staining.

References

1. "Ionisers", BioGuard Technical Information Bulletin BG-016.
2. "Floatron® Solar-Powered Ioniser", BioGuard Technical Information Bulletin BG-042.
3. "Questa PoolFresh® Ioniser", BioGuard Technical Information Bulletin BG-044.
4. R.C. Weast (ed.), "CRC Handbook of Chemistry and Physics", 57th edition, CRC Press, Cleveland OH, 1976, Section B.

The above information is supplied by Bio-Lab and represents its best interpretation of available technical information at the time of preparation. The sole purpose is to supply factual information to Bio-Lab customers. It is not to be taken out of context nor used as support for any other claim not made herein.