in turbidity the change in absorbance resulting from hmhec treatment showed a response that was characterized by a deflection point as indicated in fig3 as the concentration increased up to 6 ppm there was a sharp decrease in absorbance indicating that deposition was effectively inhibited increasing the concentration above 6 ppm had little effect on deposition the effect of hmhec on turbidity as demonstrated in fig4 shows and opposite effect there was a significant increase in turbidity as the concentration of hmhec was increased above 10 ppm the rate of increase in deposition in response to more hmhec being added was much less than that detected at 10 ppm or less a series of studies were carried out to demonstrate the effect of additions of hmhec and polyamine a on deposition and turbidity in the test system a baseline for absorbance and turbidity values in untreated systems was established mean values of 0 82 for absorbance at 200 nm and 182 for turbidity were obtained for 13 independent experiments the mean absorbance and turbidity values were then compared to results over a range of concentrations of polyamine a and hmhec the approach to this was to use the equations that described the dose response relationships in fig1 u2013 4 to predict the effect of selected concentrations of polyamine a and hmhec on absorbance and turbidity if the two materials were acting in an additive manner the effect on turbidity and deposition would be the sum of the individual effects if the effect was less than that.