Step 3.C – Determination Wait Time
The Determination Wait (Eq. 8) time is the length of the time the system waits after a corrective action to determine the
outcome. Using values found in the previous step (3.B)
Step 3.D – Decrease Threshold
The Decrease Threshold (Eq. 9) is how far the system will let the monitored residual drop from the Target Residual setting
prior to beginning disinfectant feeds. For an initial value, the Residual Increase (Eq. 6) value calculated above may be
used along with a percentage of recovery.
- Chlorinated Recovery Percentage: 70-100%
o In chlorinated systems larger corrections are acceptable since we do not have to worry about additional
chemical reactions as in the case of chloraminated systems
- Chloraminated Recovery Percentage: 50-70%
o Smaller increments are beneficial since the objective is to re-bind available ammonia without overshooting
and negatively impacting the existing residual levels
Step 4 - Continued Tuning
Once the system has made several corrections the Determination Wait Time should be matched to the dynamic conditions
of the tank, accounting for mixing, fill cycles, usages, etc. Adjustments should be made based on residual changes
witnessed after each corrective action. For most applications, Determination Wait Time should equal the length of time
until residuals have stabilized after the conclusion of a feed, with a minimum of 1 hour.
Since the Determination Wait Time will now be a known value based on operational conditions of the tank, it may be used
to further tune the corrective settings of the unit. At this point, Daily Volume (Eq. 4) may be updated if conditions have
changed. This will be used to determine an updated Feed Duration (Eq. 10) as a function of the matched Determination
Wait Time, as well as an updated Decrease Threshold (Eq. 9).
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Initial Settings
Initial Settings
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