Hach DR/700 Procedures Manual page 451

CHROMIUM, HEXAVALENT,
7.
Fill a 10-mL cell
to the 10-mL line
with the sample (the
blank). Cap.
Note: For turbid
samples, treat 25 mL of
the blank with the
contents of one Acid
Reagent Powder Pillow.
This will ensure any
turbidity dissolved by
the acid in the
ChromaVer 3 Chromium
Reagent also will be
dissolved in the blank.
8.
Place the blank in
the cell holder.
Note: In bright light it
may be necessary to
close the cell
compartment cover.
55-3
continued
9.
Press:
ZERO
The display will
count down to 0.
Then the display will
show 0.000 mg/L and
the zero prompt will
turn off.