Greensand vs DMI-65: Which Iron & Manganese Removal Media Is Better?
- Everfilt® Admin
- Oct 27
- 4 min read
If you work in water treatment, you’ve probably heard of Greensand and DMI-65®. Both are widely used filter media for removing iron, manganese, and arsenic from groundwater, but which one actually performs better for your application?
We’ll dive deep into how each media works, its strengths and weaknesses, and review real-world case studies. You’ll also find a practical checklist to help you choose the best option for your system.
Understanding the Two Media
What is Greensand™?
Greensand (and its newer variant, GreensandPlus™) is one of the oldest and most proven filtration media for iron and manganese removal. It’s made of glauconite greensand coated with manganese dioxide (MnO₂), which acts as an oxidizing agent.
As water passes through, the media oxidizes dissolved ferrous iron (Fe²⁺) and manganese (Mn²⁺) into insoluble oxides that can be filtered out. However, Greensand must be regenerated periodically using potassium permanganate (KMnO₄) or chlorine to restore its oxidizing capacity.
This means ongoing chemical handling and operational oversight, something many small systems are used to, but which can add cost and complexity.
What is DMI-65®?
DMI-65® is a newer generation of catalytic sand media developed for iron, manganese, and heavy metal removal. Unlike traditional Greensand, DMI-65® is made from activated silica with a proprietary catalytic coating.
Its key selling point: no routine chemical regeneration required. Instead, it uses dissolved oxygen in the water to catalyze oxidation, meaning it can continuously remove iron and manganese without dosing potassium permanganate.
DMI-65® is marketed as capable of achieving very low detection-level residuals for both iron and manganese, and some studies even report arsenic co-removal when used correctly.
Greensand vs DMI-65®: Key Differences at a Glance
Strengths & Weaknesses of Each Media
The Case for Greensand
Strengths
Proven reliability: Over 50 years of successful installations worldwide.
Operator familiarity: Many small utilities already use it.
Lower initial cost: Easy to procure and replace.
Weaknesses
Requires chemical regeneration: Ongoing potassium permanganate feed and handling.
More operator attention: Incorrect regeneration or pH imbalance reduces performance.
Shorter media lifespan: Typically 3–7 years before replacement is needed.
The Case for DMI-65®
Strengths
No continuous permanganate dosing: Reduces chemical cost and handling risks.
High efficiency: Case studies report effluent iron and manganese at detection levels.
Longer lifespan: Can last 5–10 years or more when operated correctly.
Effective at low oxidant conditions: Uses dissolved oxygen as the oxidizer.
Weaknesses
Higher initial media cost: More expensive per cubic foot than Greensand.
Performance varies by site: Some raw waters may still need pre-oxidation or pH correction.
Fewer long-term independent studies: Technology is newer, so large-scale historical data is limited.
Real-World Case Studies
Emalahleni, South Africa: A municipal system using DMI-65® achieved iron and manganese removal to <0.01 mg/L without KMnO₄ regeneration. The site also reported reduced backwash frequency and lower operating costs.
Mining site in Western Australia: DMI-65® treated mine water containing high iron and manganese loads, reducing concentrations to potable levels using only aeration and filtration.
India (industrial plant): A DMI-65® installation reported consistent manganese removal and low maintenance for over five years of continuous operation.
Greensand Success Stories
U.S. municipal well systems: Thousands of small towns rely on manganese Greensand™ for iron and manganese removal.
Industrial groundwater remediation: Greensand filters are used as a final polishing step after oxidation tanks, producing stable long-term compliance with low iron and manganese effluent levels.
Which One Should You Choose?
The answer depends entirely on your raw water chemistry, budget, and operational preferences.
Choose Greensand if:
You have moderate iron/manganese levels.
Operators are trained to handle chemicals like KMnO₄.
You want a lower upfront media cost & proven performance.
Choose DMI-65® if:
You want to minimize chemical handling & permanganate storage.
You need ultra-low residual levels (for potable or industrial-grade water).
You operate in remote or resource-limited locations where chemical logistics are difficult.
Practical Checklist Before You Decide
Test your raw water (Fe, Mn, pH, TOC, arsenic, sulfide).
Run a pilot test with each media under identical conditions.
Compare lifecycle costs, not just media price.
Evaluate backwash requirements & filter hydraulics.
Train operators on whichever system you choose.
There’s no universal winner between Greensand and DMI-65®; both have clear strengths.
Greensand remains a trusted, cost-effective solution for conventional systems with trained operators and manageable chemical logistics.
DMI-65® offers a modern, lower-maintenance alternative that eliminates permanganate dosing and has proven itself in challenging industrial and municipal applications.
Ultimately, the best choice comes down to your water chemistry, budget, and operational goals. Pilot testing both is the smartest way to make a confident decision.