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Product Description (1)

The Floatron® is a portable solar-powered water purifier that utilizes ionisation to control microbial growth. Sunlight strikes a photovoltaic cell (solar panel) at the top of the device, generating a low electrical current across two immersed electrodes. Oxidation occurs at a copper alloy anode (described in the sales brochure as a "mineral" electrode), liberating Cu2+ ions into the water. These ions destroy potentially harmful bacteria and limit algal growth, thereby negating the need for high levels of chlorine and the presence of algaecidal additives.

 

Precautions1

The Floatron cannot be used in the presence of additives intended as replacements for chlorine, such as Baquacil, nor any water clarifier or conditioner which removes metal ions from solution. Superchlorination is also discouraged as it can lead to precipitation of the copper as insoluble compounds. The solar panel must be treated with care; sharp objects may scratch and possibly even tear the cell.

 

Critical Assessment of Claims

The sales brochure for the Floatron unit (1) claims numerous advantages over conventional pool treatment using compounds such as hypochlorite. The following discussion considers a number of the claims made.

 

1. 2000 times more effective against algae than chlorine. This statement is apparently based upon studies undertaken by the University of Arizona. The use of copper as an algaecide was assessed in an earlier TIB, (2) the key statement there being that "... under laboratory and field controlled conditions, copper ions have proven to be effective algaecides but their effectiveness in pool and spa water treatment appears questionable". This is primarily due to the increased chances of precipitation as insoluble salts, thereby diminishing the availability of Cu2+ ions. It should be noted that Floatron does recommend a low level of chlorine be maintained in the pool, acknowledging the poor performance of copper as a bactericide. In addition, no comparisons are drawn with other purification schemes, such as the use of cyanuric acid.

2. Maintains a stable pH level. This claim would seem to be based on the fact that copper ions alone will not shift the pH balance all that much, provided the levels of anions such as hydroxide, carbonate and sulfide remain low. It should be added, however, that copper ions do not buffer pH, and that the pool water will still require adjustment into the ideal pH range (7.4 - 7.6) in much the same manner as for chlorination.

3. Softens hard bore water. "Hard" water is due to the presence of calcium and magnesium carbonates. As the solubility of copper carbonate is lower than for either CaCO3 or MgCO3, (3) it should preferentially precipitate out, so this claim is reasonable. However, the downside will be a blue CuCO3 precipitate that may reduce the clarity of the pool and will reduce the effectiveness of copper as an algaecide. (2)

4. No "tedious" testing of pool water required. The quoted "ideal" copper concentration should lie in the range 0.2 to 0.5 ppm. The manufacturer suggests testing once a week until the pool owner is "... familiar with the operation of the Floatron". Given that (a) the level of sunlight falling on the photovoltaic cell may vary significantly from day to day, altering the electrical current and, hence, the rate of production of copper ions, and (b) it is undesirable to exceed 1 ppm copper, (4) this advice is rather dubious. Floatron recommends residual chlorine be maintained at between 0.2 and 0.5 ppm (ie. identical to the copper level) when using the device. At these levels, chlorine is detectable using DPD as a pale pink discolouration of the test solution, so chlorine testing will still be feasible and, in fact, advisable.

5. Non-toxic minerals used. Without exact details of the composition of all the Floatron's components, it is difficult to confirm this. However, it would seem to be a valid statement provided generated copper ion levels are kept to recommended levels.

6. No irritation to the eyes or skin. As a small amount of chlorine is still required, the possibility always exists for the formation of chloramines from the reaction of hypochlorite and ammonia or amines arising from organic waste in the pool. Bathers with high sensitivities toward chloramines may therefore experience some eye soreness. Under normal circumstances, copper should not give rise to any skin or eye irritations.

7. Will not turn blonde hair green. A novel claim given that copper will turn blonde (and other) hair green if residual halogens are present.2 Whether Floatron's recommended chlorine level (0.2 - 0.5 ppm) is sufficient to promote this undesirable property would require further investigation.

8. One-off cost. This is a misnomer, as the copper anode will eventually oxidise completely, necessitating a new electrode. The cited cost of this replacement was $A45.00 at the time this TIB was prepared. To make a direct cost comparison between chlorination and the Floatron, details of unit cost and typical electrode operational lifetime are necessary.

 

One other point worth making is that being solar-powered may have severe drawbacks for the winter maintenance of the pool. In other words, what happens when there isn't any sunlight falling on the device for prolonged periods? This will largely depend upon whether the unit has any form of electrical storage circuit and how efficient the photovoltaic cell is at converting solar radiation into usable electrical energy. Obviously, potential problems arising from a lack of sunlight will be significantly less for pool owners in the more northern regions of Australia, such as Queensland and NT.

 

Conclusions

In his 1988 text, Ben Selinger of the Australian National University advised against pool water purifiers based on ionisation.4 In light of concerns expressed above and in TIB BG-016, caution should still be exercised in the use of ionisers for swimming pool and spa applications.

 

References

1. Floatron Sales Brochure and Operating Instructions, Floatron (Australia) Pty Ltd., 10 Thomas Street, Noosaville QLD 4566.

2. "Ionisers", Bio-Lab Australia Technical Information Bulletin BG-016, and references therein.

3. D.A. McQuarrie and P.A. Rock, "General Chemistry", 3rd edition, Freeman, New York, 1991, p. A-24.

4. B. Selinger, "Chemistry in the Market Place", 4th edition, Harcourt Brace Jovanovich, Sydney, 1988, pp. 573-575.

 

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

Last update: 30 April 2003