What does the Hach DR300 Manganese model measure?

The Hach DR300 Manganese model measures dissolved (reduced) manganese in the range 0.006 to 0.700 mg/L Mn using PAN Method 8034. It measures Mn2+ (manganous ion) — the soluble, reduced form. It does NOT measure oxidized manganese in particulate form (MnO2, MnOOH) without a separate acid digestion pre-treatment step. In water systems, dissolved Mn2+ is the form found in anoxic groundwater and at the bottom of stratified lakes and reservoirs; it becomes the black or dark brown particulate MnO2 when oxidized during treatment.

What is the EPA standard for manganese in drinking water?

The US EPA Secondary Maximum Contaminant Level (SMCL) for manganese is 0.05 mg/L (50 µg/L). SMCLs are non-enforceable guidelines related to aesthetic quality — manganese causes black or brownish staining of laundry and plumbing fixtures and gives water a metallic taste at concentrations above the SMCL. In 2004, EPA issued a health advisory for manganese at 0.3 mg/L based on neurological effects from long-term exposure, and at 1.0 mg/L as a short-term health advisory for infants. The WHO guideline value is 0.08 mg/L. The DR300 Manganese range of 0.006-0.700 mg/L covers all these reference values.

Why does the Hach DR300 Manganese require a 2-minute wait before reading?

The PAN (1-(2-Pyridylazo)-2-naphthol) reagent requires 2 minutes to fully chelate manganese ions and develop stable color. Reading before 2 minutes produces a falsely low result because the metal-ligand complex is incompletely formed. After 2 minutes, the orange-yellow color is stable for at least 5 minutes. Read between 2 and 5 minutes from reagent addition for accurate results. Unlike some methods where delayed reading causes color to fade, the PAN-manganese complex is relatively stable within this window.

How is manganese related to iron testing in well water?

Manganese and iron frequently occur together in anoxic groundwater because both are reduced to soluble forms under low-oxygen conditions. Iron (Fe2+) and manganese (Mn2+) are both mobilized when dissolved oxygen is depleted, and both precipitate as colored solids when oxidized — iron as red-brown rust (Fe2O3) and manganese as black/dark brown particles (MnO2). They are treated with similar oxidation-filtration systems, but manganese requires a higher oxidation potential than iron (potassium permanganate or greensand filtration is typically needed). Measure both on separate DR300 models — the FerroVer iron reagent does not respond to manganese, and the PAN manganese reagent does not respond to iron at normal water treatment concentrations.

Product Review & Technical Reference — Hach DR300

Hach DR300 Manganese Pocket Colorimeter: Complete Review & Reference (2026)

PAN Method 8034 • 0.006–0.700 mg/L Mn • Dissolved Manganese • IP67

Source: Hach DR300 User Manual DOC022.97.90639 Ed.5 (09/2021) • Method 8034 (PAN Indicator)

Hach DR300 Manganese-HR pocket colorimeter display showing mg/L Mn measurement

Water treatment operator using Hach DR300 Manganese pocket colorimeter at an industrial water treatment plant

Hach DR300 Pocket Colorimeter — Manganese (PAN Method 8034)

0.006–0.700 mg/L Mn dissolved • IP67 • EPA SMCL 0.05 mg/L. Reagents sold separately.

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Method

PAN Method 8034

Range

0.006–0.700 mg/L Mn

Measures

Dissolved Mn²+ only

EPA SMCL

0.05 mg/L Mn

WHO Guideline

0.08 mg/L Mn

Read Window

2–5 min after mixing

Color Developed

Orange-yellow

IP Rating

IP67 Waterproof

Manganese in Water Supply — The Problem and the Measurement

Manganese is a naturally occurring element that enters water supplies primarily from geological sources — the weathering of manganese-bearing rocks and minerals. It is particularly common in groundwater and in water from the hypolimnion (deep, anoxic layer) of stratified lakes and reservoirs. Under low-oxygen conditions, insoluble oxidized manganese (MnO₂, brown-black particulates) is reduced to soluble Mn²+ (manganous ion, colorless), which dissolves in the water.

When this manganese-laden water reaches oxygenated conditions — either through treatment (aeration, chlorination, potassium permanganate addition) or simply upon contact with distribution system piping — the Mn²+ reoxidizes and precipitates as dark brown or black MnO₂ particles. These deposits cause black staining of laundry, plumbing fixtures, and plumbing infrastructure, and give water an objectionable metallic taste.

Dissolved vs Total Manganese — Critical Distinction

The DR300 Manganese measures dissolved Mn²+ only. PAN Method 8034 reacts with soluble, reduced manganese in its Mn²+ oxidation state. It does NOT measure particulate MnO₂ or other oxidized manganese forms without a separate acid digestion pre-treatment. If your sample has visible turbidity or black/dark particles, filter through a 0.45-micron membrane before testing to measure dissolved manganese only, or perform an acid digestion (heat + HNO₃) to convert all manganese forms to Mn²+ before testing for total manganese.

Sample Type	What DR300 Measures	Pre-Treatment Required
Clear groundwater sample	Dissolved Mn²+ — accurate without pre-treatment	None required
Turbid or colored sample	Dissolved Mn²+ only (particles settle or scatter light)	Filter through 0.45-micron membrane before testing
Oxidized/treated water with MnO₂ particles	May underestimate total manganese — particulate Mn not measured	Acid digestion (HNO₃ + heat) to dissolve all Mn forms; then test
Distribution system sample with black particles	Dissolved fraction only; particles not measured	Acid digestion for total manganese

Manganese vs Iron — Two Parameters, Two Instruments

Manganese and iron share similar geochemistry and are frequently co-occurring in groundwater and anoxic source water. They require separate DR300 models because their colorimetric methods are completely different — and the reagents do not cross-react.

Parameter	DR300 Model	Method	Range	Reagent
Iron (dissolved + total)	DR300 Iron FerroVer®	FerroVer, Method 8008	0.02–5.00 mg/L Fe	FerroVer Powder Pillow or AccuVac
Manganese (dissolved)	DR300 Manganese	PAN, Method 8034	0.006–0.700 mg/L Mn	PAN Indicator Solution
FerroVer does not respond to manganese at water treatment concentrations. PAN does not respond to iron. Both instruments are needed when monitoring water sources with co-occurring iron and manganese.

EPA & WHO Standards for Manganese

Standard	Value	Basis
EPA SMCL (aesthetic)	0.05 mg/L Mn	Non-enforceable; staining, taste, and odor above this level
EPA Health Advisory (long-term)	0.3 mg/L Mn	Neurological effects from chronic exposure; adults
EPA Health Advisory (infant short-term)	1.0 mg/L Mn	Neurological effects in formula-fed infants
WHO Guideline Value	0.08 mg/L Mn	WHO Guidelines for Drinking-water Quality, 4th Ed.
EU Parametric Value	0.05 mg/L Mn	Council Directive 98/83/EC
The DR300 range of 0.006–0.700 mg/L covers all reference values above. The 0.006 mg/L detection limit allows monitoring well below the 0.05 mg/L SMCL.

How PAN Method 8034 Works

PAN (1-(2-Pyridylazo)-2-naphthol) is a highly selective chelating agent for transition metals. In acidified water containing Mn²+, PAN forms a stable orange-yellow metal-chelate complex. The color intensity at the measurement wavelength is proportional to the manganese concentration. The reaction is completed in approximately 2 minutes at room temperature and the color is stable for at least 5 minutes within the read window.

The method is specific to dissolved Mn²+ because only the reduced, soluble form reacts with PAN under the test conditions. Oxidized manganese species (Mn³+, Mn⁴+) in particulate form do not dissolve and therefore do not react.

Standard Test Procedure

Filter sample if turbid (0.45-micron membrane)

If measuring dissolved manganese only, filter turbid or colored samples through a 0.45-micron membrane filter before testing. For total manganese, perform acid digestion instead of filtering.

Fill sample cell to the specified volume

Use the appropriate cell type for your DR300 configuration. Triple-rinse cell with sample before the measurement fill.

Add Ascorbic Acid reagent — mix

Ascorbic acid acts as a reducing agent and removes any traces of oxidized manganese back to Mn²+ in the dissolved fraction, and eliminates chlorine interference. Add and invert to mix.

Add Alkaline Cyanide reagent — mix

Masking reagent that complexes iron and other interfering metals, preventing them from reacting with PAN. Critical for samples with elevated iron. Add and invert to mix.

Add PAN Indicator Solution — mix — start 2-minute timer

Add the PAN indicator. Cap and invert to mix. Orange-yellow color develops if dissolved manganese is present. Start the 2-minute timer immediately.

At 2 minutes: zero with blank, then read sample

Zero the instrument with the blank cell (sample water with no reagents), swap to the sample cell, press READ. The read window is 2 to 5 minutes from PAN addition. After 5 minutes, color may begin to shift.

Interferences

Interferent	Effect	Treatment
Iron (Fe)	PAN reacts with iron; Alkaline Cyanide masking reagent in the procedure eliminates this interference up to approximately 5 mg/L Fe	Alkaline Cyanide reagent (step 4) masks iron; no additional treatment needed below 5 mg/L Fe
Iron >5 mg/L	Positive interference; Alkaline Cyanide masking capacity exceeded	Dilute sample if iron is very high; or treat with excess EDTA to complex iron before masking
Residual chlorine	Oxidizes Mn²+ before PAN reaction; falsely low results	Ascorbic acid (step 3) eliminates chlorine; ascorbic acid must be added first
Copper (Cu >1 mg/L)	Reacts with PAN; positive interference	Alkaline Cyanide also masks copper; may need higher masking reagent dose at very high Cu
Turbidity/particulate MnO₂	Does not react with PAN but may cause optical interference	Filter through 0.45-micron before testing dissolved Mn
Temperature <10°C	PAN chelation rate decreases at low temperature	Allow cold samples to warm to room temperature; extend wait time to 3 minutes

Treatment Context — Manganese Removal

The DR300 Manganese is used throughout the treatment process for monitoring and process control:

Treatment Point	Monitoring Purpose	Typical Range
Raw groundwater / source water	Establish baseline; size treatment system	0.01–3.0+ mg/L (widely variable by geology)
After aeration or pre-oxidation	Verify manganese oxidation for filtration	Should decrease vs. raw; oxidized Mn²+ precipitates
After greensand or MnO₂ filtration	Confirm removal; monitor filter exhaustion	Should be <0.05 mg/L in product water
After KMnO₄ treatment	Confirm adequate dose; excess KMnO₄ causes pink water	Target <0.05 mg/L in filter effluent
Finished water / distribution	SMCL compliance; staining complaint investigation	Target <0.05 mg/L; customer complaints typically at >0.1 mg/L

Manganese treatment note: Unlike iron, manganese removal requires a stronger oxidant or a longer contact time. Chlorine at typical doses is less effective at oxidizing manganese than iron, especially at low pH. Potassium permanganate (KMnO₄), ozone, or biological manganese oxidation (manganese-oxidizing bacteria on filter media) are commonly used. Greensand filters (glauconite coated with MnO₂) catalyze the oxidation at the filter surface. The DR300 Manganese is the standard instrument for monitoring each stage of these treatment processes.

Reagents & Parts Reference

Item	Hach Item No.	Notes
PAN Indicator Solution	2289826 (verify)	Primary colorimetric reagent; added last in the sequence
Ascorbic Acid Reagent	Included in Mn test kit	Eliminates chlorine interference; added first
Alkaline Cyanide Reagent	Included in Mn test kit	Masks iron and copper; add before PAN
DR300 instrument cap	LPV445.97.08100	Must be installed before ZERO or READ
Sample cell cap	LPV445.97.08200	Caps cell between reagent additions
Batteries, AAA (4-pack)	Standard AAA alkaline	Replace all 4 simultaneously
Alkaline Cyanide reagent contains cyanide compounds — handle with care, wear gloves and eye protection, do not acidify (generates HCN gas). Dispose as hazardous waste. Confirm current item numbers at hach.com.

Alkaline Cyanide safety: The Alkaline Cyanide masking reagent contains potassium cyanide (KCN). Never acidify this reagent or any waste containing it — acid converts cyanide to hydrogen cyanide (HCN) gas, which is acutely toxic. Dispose of cyanide-containing waste as hazardous waste. Work in a ventilated area. Wear gloves and eye protection. Keep away from acids.

Hach DR300 Pocket Colorimeter — Manganese

PAN Method 8034 • 0.006–0.700 mg/L Mn dissolved • IP67. EPA SMCL 0.05 mg/L. Reagents sold separately.