205
ESPLXD-ET Controller
Irrigation Amount and Station Run
Times
Irrigation Amount
The Irrigation Amount represents how many inches (or mm) of water
is applied to your landscape during each program start time. The
Total Irrigation Amount is the Irrigation Amount setting multiplied by
the number of start times. This is the amount of water that needs to
evaporate before the ET Manager will allow watering to start again.
The optimum Total Irrigation Amount is based on your soil type and
the plant’s root depth (refer to the table in the Total Irrigation Amount
section). Each program has its own Irrigation Amount setting to
accommodate different landscape watering needs.
Peak Season ET Method
When the ET Manager is being installed on an established site that
already has a schedule, the ‘Peak Season ET’ method can be used to
determine the Total Irrigation Amount. This method requires that the
irrigation schedule be set to peak season watering. The next step is to
determine what the average peak season ET value is for the area, which
can be found by looking at the Historical ET settings and finding the
highest value (typically July or August). Then multiply the average peak
season ET value by the typical number of days between watering during
the peak season schedule. The result is your Total Irrigation Amount.
b
b
NOTE
: This method should be used before the watering days and
run times are set.
Peak Season ET Method Example
If a site has typically watered every other day during the peak of the
season, and the Historical ET Values for that time of the year were 0.22,
then the Total Irrigation Amount for the site is 0.44 (0.22 x 2 days).
Change the setting for all available watering days to ON as the ET
Manager will now determine which days to water.
b
b
NOTE:
Keep in mind that the Total Irrigation Amount needs to
be divided by the number of start times in the program before
entering the value for the setting.
Total Irrigation Amount
Run time settings programmed in the sprinkler controller correspond to
Irrigation Amount settings in the ET Manager.
Soil Type
Estimated Total Irrigation Amount (inches)
Root Depth (inches)
2
4
6
8
12
18
Sand
0.02
0.05
0.07
0.10
0.14
0.22
Fine Sand
0.07
0.14
0.22
0.29
0.43
0.65
Loamy Sand
0.08
0.17
0.25
0.34
0.50
0.76
Sandy Loam
0.12
0.24
0.36
0.48
0.72
1.08
Sandy Clay
0.16
0.32
0.48
0.64
0.96
1.44
Loam
0.17
0.34
0.51
0.68
1.02
1.53
Sandy Clay
Loam
0.15
0.30
0.45
0.60
0.90
1.35
Silty Loam
0.20
0.40
0.60
0.80
1.20
1.80
Clay Loam
0.20
0.40
0.60
0.80
1.20
1.80
Silt
0.17
0.34
0.51
0.68
1.02
1.53
Silty Clay
Loam
0.20
0.40
0.60
0.80
1.20
1.80
Silty Clay
0.13
0.26
0.38
0.51
0.77
1.15
Clay
0.09
0.18
0.27
0.36
0.54
0.81
ESPLXD-ET user-manual (670504-01) artwork_120716.indb 205
7/16/2012 3:49:06 PM
