Alkalinity averaged 1.5 meq L−1 at the start of the spiking trial,and decreased by 0.23 meq L−1 at the end of the sampling period.The pH in all systems averaged 7.60 and ranged from 7.3 to 7.8during the trial. Both alkalinity (p = 0.776) and pH (p = 0.367) didnot differ between treatment groups during the spiking trials.