Table 4: Estimated pit initiation times and computed pit propagation rates based on and If or was not observed during test, pit initiation time could not be estimated. Tests are grouped by respective adjustments to control water quality and large-scale results are bolded.

Test numberPropagation rate ( )
Initiation time (days)Maximum Average

Control
 S1 10 1011.711.73.93.9
L1 354.84.62.72.6

Chlorine
 S2
 S3
 S4141978.03.83.31.7
 S549459.98.84.23.8
 S6141416.416.43.13.1
L24074.73.23.21.91.9

Phosphate
 S7282516.414.23.73.5
 S8323214.914.93.93.9
 S9
 S10
 S11
 S12
L377772.82.81.71.7
L4

Silica
 S13141411.311.33.83.8
 S14161618.218.22.62.6
 S15
 S16
L577352.82.51.11.0
L6

Organic matter
 S17212116.716.73.03.0
 S18141410.810.83.13.1
 S1948443.12.81.91.7
 S2028263.23.11.91.8
 S2120208.78.74.54.5
L770296.54.92.82.2
L8217713.32.11.91.2

Alkalinity
L935155.85.13.12.8
L1035150.70.70.50.5