Electrolytically generated copper and silver ions have been used for many years as a method of purifying swimming pool water. Although this method is capable of controlling algae and bacteria, it has been regarded by most authorities to be too slow in its response against micro-organisms. However, when a suitable oxidiser is present with the copper and silver ions, the response is improved by several orders of magnitude and thus the method becomes a viable alternative to chlorination. The purpose of this investigation was to compare the efficacy of chlorine with The Aquabrite System against E. coli, Ps. aeruginosa and raw sewage bacteria in synthetic swimming pool water to which organic nitrogen (urea) had been added, as proposed by Yahya et.al., (1989).

Results of the tests indicated that copper and silver ions (900 ug/L and 50 ug/L, respectively) when used in conjunction with 10 mg/L Aquabrite reduced numbers of E.coli by greater than 3.1 log10 in approximately 0.5 minutes. The chlorinated system (1.2 mg/L chlorine) inactivated E.coli numbers 1.1 log10 in the same time interval. See figure 1. (test results are presented in appendix 3).

Results were obtained for Ps. aeruginosa which indicated that the organism resisted the effects of chlorination (1.2 mg/L chlorine) after an initial reduction of 2.2 log10 in approximately 0.5 minutes, as no further reduction was observed even on prolonged contact. See figure 2 .(test results are in appendix 3).

The Aquabrite System reduced bacterial numbers by 1.2 log10 after approximately 0.5 minutes and continued to reduce bacterial numbers by 3.9 log10 at 4 minutes contact time. The same water which was stored for 14 days, and which had no further chemical treatment, was re-tested and demonstrated an improved anti-bacterial performance by reducing bacteria numbers by 3.0 log10 in approximately 0.5 minutes and 5.4 log10 in 4 minutes contact time.

In another trial, raw sewage bacteria were obtained from Warriewood Sewage Treatment Plant and after filtration and dilution, used to inoculate the test and control tanks.
Results indicated that the Aquabrite System was able to reduce bacterial numbers by 2.6 log10 in approximately 0.5 minutes, but the results for chlorine (1.2 mg/L) followed a similar response to that which was observed for Ps. aeruginosa. After an initial reduction of 1.8 log10 for 0.5 minutes contact almost no further reduction took place. Aquabrite, however, continued to reduce bacterial numbers to 4.4 log10 after 8 minutes contact time; see figure 3 (test results are presented in appendix).