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The following Technical Information Bulletin is a re-write of a Competitive Products Update prepared by Technical Information Services, Bio-Lab, Inc., Decatur GA on 4 April 2001.

The Frog™ cartridge marketed by King Technology, Inc. and the Sildate® system marketed by N. Jonas, Inc. received a great deal of consumer attention in the US during the 2000 and 2001 seasons. At the time of writing, the Frog system was also available in Australia. Both systems employ metallic ions as the basis for sanitation. Whilst Frog provides two options for operation - one involving the maintenance of a low chlorine residual - the addition of chlorine is discouraged for pools running the Sildate system.

Frog Mineral Cartridge

Fitting into a basic King feeder, the Frog cartridge utilises a mineral bed containing zinc and silver(I). The cartridge inlet can be adjusted for sending water through the mineral bed or, if some chlorine is desired, through a small bed of trichloroisocyanuric acid tablets and the mineral bed at the same time. Enhanced bactericidal action is claimed for the activated surface of the mineral bed at the site of the silver. The zinc component is claimed to "clean off" the silver in the mineral bed reservoir, whilst providing a degree of algae control. The persulfate-based Oxy-Gen Plus Non-Chlorine Shock and Clarifier is added two to three times per week as a maintenance oxidiser.

At the time of writing, no reports concerning the Frog system and its acceptance or performance have been received from the field. Literature searches have yielded information showing zinc to be an effective algaecide, but only for a limited number of algae species, at high zinc residuals and with poor long-term results. The documentation supplied with the Frog cartridge recommends a chlorine residual of a mere 0.5 ppm when operating in "low chlorine" mode. However, the NRA-registered label for all trichlor tablets likely to be used in the feeder requires at least a 2-ppm chlorine residual, placing the Frog directions at odds with Australian regulatory requirements. Even more perturbing is the idea of a Frog cartridge operating with no residual chlorine. Sanitation would then rely solely on the water passing through the mineral bed but, in a situation similar to ozone, this would provide no residual of bactericidal agent within the body of the pool.

Sildate System

The Sildate system uses silver, but not in the common +1 oxidation state (silver(I), Ag+) as found in ioniser systems like the Questa PoolFresh or Nature2 units. Rather, Jonas says that the silver is present in the rarer +2 state (silver(II), Ag2+). Investigations performed by Bio-Lab US on samples of the product from the field indicates this may be better viewed as a mix of +1 and +3 states. Silver(III) is a strong oxidiser and an excellent bactericide.(1) However, it is also quite unstable and will revert to silver(I), thus becoming a much slower bactericide and more vulnerable to precipitation. Furthermore, not much is known about the human or aquatic toxicity of either silver(II) or silver(III).(2) The addition of Sildate Energize is designed to "re-energise" the silver(I) ions back into the higher oxidation state of either +2 or +3. Energize is a persulfate shock with an active oxygen level of approximately 6.5%. For comparison, the active oxygen content of the monopersulfate in BioGuard Oxy- Sheen is 4.3%.

The silver in the Sildate system is in suspension, so it is not unusual to see deposits on the bottom of pools following the addition of the product. Predictably, reports from the field indicate significant problems with staining. One report centred on the staining occurring on hard plastic items like steps, ladders and eyeballs in vinyl pools, whilst a second identified pool surface staining as a problem (most likely on gunite). Jonas, Inc. has indicated to the dealer experiencing surface staining that it will pay to correct the problem and put the pool back onto chlorine. This conversion has to be accomplished through a drain and refill - currently the only known method of converting a Sildate pool to another sanitation system. Jonas has indicated that excessive additions of the Energize may be to blame for some of the problems encountered.

Notably, the only product tested for use with the Sildate system is Energize. At this time, Bio-Lab is not recommending the use of any BioGuard or SpaGuard products in a Sildate-treated pool. We cannot be sure of the results of the addition of these products and feel that this would place us at a difficult situation should a problem occur. Again the only conversion process that we know of is a drain and refill. Jonas has indicated that starting up a 75,000-litre pool on the Sildate program will cost approximately $US98. Monthly maintenance would be about $US80 for the same pool.

References
1. A.J. Bard, Journal of the American Chemical Society, Volume 113, 1991, pp. 4192-4198.
2. British Columbia Ministry of Environment, Lands & Parks, Ambient Water Quality Criteria for Silver, at www.env.gov.bc.ca/epd/cpr/criteria/awqcfs.html.

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.
TIB No. BG-071
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Last update: 30 April 2003