Hach DR/700 Procedures Manual page 167

SILICA, HR,
10.
Fill a second
10-mL cell to the
10-mL line with
sample (the blank).
13.
Within 3
minutes after the 2
minute period, place
the prepared sample
in the cell holder.
Note: In bright sunlight
it may be necessary to
close the cell
compartment cover.
continued
11.
Place the blank
in the cell holder.
Note: In bright sunlight
it may be necessary to
close the cell
compartment cover.
14.
Press:
READ
The display will
count down to 0.
Then the display will
show the results in
mg/L silica.
42-83
12.
Press:
ZERO
The display will
count down to 0.
Then the display will
show 0.00 mg/L and
the zero prompt will
turn off.