LaMotte DPC-52 Water Testing Laboratory - Manual (Page 11)

IRON
Iron is a major source of staining in swimming pools. The unattractive orange-brown
discoloration may appear on pool surfaces and also appear as a fine-particle sediment.
Iron is readily oxidized by chlorine and oxygen in the water and may settle to the bottom
as the insoluble ferric (Fe+3) form of iron. Usually levels of iron above 0.2 - 0.3 will
cause staining to pool surfaces, therefore iron levels should be maintained below this
concentration.
RANGE:
0.1 - 7.0 ppm
METHOD:
Ferric Iron is reduced to ferrous iron and subsequently forms a
colored complex with bipyridyl for a quantitative measure of
total iron.
INTERFERENCE:
Copper in excess of 5.0 ppm may cause interference.
PROCEDURE
1. Rinse and fill colorimeter tube (0967) to the 10 mL line with water sample.
2. Use the 0.5 mL pipet (0369) to add 0.5 mL of *Iron 1 Reagent (WL-4450) to the
sample in the tube.
3. Use the 0.1 g spoon (0699) to add one level measure of *Iron 2 Powder (WL-4451)
to the sample. Cap tube and shake vigorously for 10 seconds. If a cloudiness persists
in test sample, shake vigorously for another 10 seconds. (If the Iron concentration is
expected to be greater than 3.0 ppm, add a second level measure of *Iron 2 Powder
to ensure color development.)
4. Wait 3 minutes for maximum color development. With the “Iron” text appearing on
the meter display, place the treated sample into the colorimeter chamber. As soon as
the display stabilizes, read result in ppm Iron.
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