dimethyl hydantoin dantochlor u00ae sodium hypochlorite dantobrom u00ae or sodium hypobromite and a performance additive described in table 4 were prepared by mixing the appropriate amounts of the ingredients in tap water at a temperature of about 37 u00b0 c and a ph of about 8 the degeneration of the performance additives tested was determined by measuring the residual oxidant halogen concentrations of the solutions over time as follows the tests were performed in a water bath maintained at 37 u00b0 c and an orbital shaker in order to keep the performance additives dispersed in the solutions aliquots were taken at regular intervals over a 30 minute period and measured for residual slimicide concentrations using the standard diethyl p phenylene diamine dpd methodology described in palin a t chemistry and control of modem chlorination la motte chemical 1973 the oxidant halogen loss rates were determined from first order linear regression plots of the residual oxidant halogen concentrations over time the results are shown in table 5 the bactericidal efficacy of each slimicide in table 6 was determined according to the procedure described in example 2 except the incubation time was 30 minutes instead of 3 hours and the initial concentration of slimicide was about 20 ppm expressed as cl 2 the bactericidal efficacy rate of each slimicide was determined by dividing the observed log reduction in the bacterial count by the 30 minute contact time the bactericidal efficacy rate at 2 ppm of slimicide expressed as cl 2 was extrapolated from the results for 20 ppm of slimicide expressed as cl 2 by assuming a first order behavior in other words the bactericidal efficacy rate at 2 ppm of.