Greensand serves as a powerful filter media used in water filtration systems to solve common water quality problems in well water. Manufacturers derive it from naturally occurring glauconite and treat it with a manganese dioxide coating that acts as a catalyst for oxidizing soluble iron and manganese in raw water.
This specialized coating allows the media to convert dissolved iron and manganese into solid particles, which the filter then removes from the water. Greensand consistently delivers high-efficiency performance and has earned a strong reputation for reliability in residential, commercial, and industrial applications.
If you’re dealing with iron stains, metallic tastes, or other water quality issues, greensand filters provide a dependable way to improve your water and protect your system.
How Greensand Filters Work
The effectiveness of greensand filters lies in the manganese dioxide coating that covers the filter media. As water passes through the greensand filter, the manganese dioxide acts as a catalyst, triggering an oxidation reaction that transforms dissolved iron and manganese into solid particles.
These particles are then trapped within the filter bed, effectively removing them from the water. In addition to iron and manganese, greensand filters can also remove hydrogen sulfide, arsenic, and radium from well water supplies, making them a versatile choice for a range of water treatment needs.
To maintain their efficiency, greensand filters are periodically regenerated using potassium permanganate, which restores the oxidizing power of the manganese dioxide coating. This process ensures that the filter continues to work effectively, providing clean, contaminant-free water for your home or business.
Types of Greensand
Water filtration systems typically use two types of greensand media: manganese greensand and Greensand Plus. Manganese greensand contains a glauconite core coated with manganese dioxide, which binds ionically to the surface and effectively removes iron and manganese from well water.
Greensand Plus improves on the original by using a silica sand core with a manganese dioxide coating fused directly to the surface. This fused coating increases durability, boosts filtration efficiency, and extends the media’s lifespan. It also resists fluctuations in water chemistry, making it a strong choice for a broader range of treatment systems.
Both types remove iron, manganese, and other contaminants effectively, but experts often recommend Greensand Plus for systems that require higher performance or must handle variable water conditions.
Benefits and Applications
Greensand filters deliver powerful water treatment with a range of benefits. They efficiently and reliably remove iron, manganese, hydrogen sulfide, arsenic, and radium from well water. The media regenerates easily with potassium permanganate, allowing the system to operate smoothly with minimal maintenance year after year.
You can use greensand filters in residential, commercial, and industrial systems, making them ideal for a wide variety of applications. In areas with high levels of iron and manganese, these filters help prevent staining, unpleasant tastes, and odors.
You can also combine greensand filters with other treatment methods, such as chlorine or ozone, for added protection. With their long-standing performance and user-friendly operation, greensand filters provide a trusted solution for clean, safe water.
Frequently Asked Questions (FAQs)
1. What are “greensand” iron filters?
Greensand filters use a specially formulated filter media made from a naturally mined form of glauconite greensand. The greensand filter media has a special coating of manganese oxide, which oxidizes iron, manganese, and iron in the water upon contact with the filter media.
Greensand filters require a type of purple powder, potassium permanganate to regenerate and clean the greensand filter media. This process is called regeneration, and it restores the manganese dioxide coating on the media, ensuring effective contaminant removal. Potassium permanganate is introduced via chemical feeds to enhance the oxidation process and maintain filtration efficiency.
An alternative to Greensand Iron Filters is the Pro-OX non-chemical air charger iron filters. Other alternative media include Filox, Katalox Light, and Birm, which do not require chemical regeneration, have higher temperature and pressure tolerances, and can treat similar or higher contaminant levels.
2. How does a Greensand Filter remove iron and manganese from water?
Iron and manganese are metals often found dissolved in water. Iron and manganese cause stains when exposed to air in the laundry, bath, etc., by oxidizing or “rusting.” The greensand filter media oxidizes dissolved iron and manganese on contact as the water flows through the greensand filter, which causes these elements to precipitate (or form solids) in the bed of the filter.
The iron filter backwashes these small particles to drain every few days in the middle of the night (or some other preset time), thereby cleaning and restoring the filter media. Backwash and regeneration cycles occur at specific times, such as every few days or at preset intervals, to maintain filter performance and longevity. To provide the oxidizing power to precipitate these metals, the filter is automatically cleaned and restored with potassium permanganate (a purple liquid) during each backwash cycle.
3. Is potassium permanganate toxic or harmful?
Potassium permanganate is a powerful oxidizer and, similar to chlorine, can cause skin irritation or burns if direct contact were to occur. But, no permanganate is added to the filtered water. The permanganate is only used to backwash and clean the greensand filter media. A special rinse cycle makes sure the filter bed is free of any permanganate residual.
4. What Is the Difference Between Greensand and Greensand-Plus Filters?
The main difference lies in the media’s core material and how the manganese dioxide coating adheres to it. GreensandPlus uses a silica sand core with a coating that fuses directly to the surface, while manganese greensand uses a glauconite core with a coating that binds ionically.
The silica sand core in GreensandPlus allows it to perform better under challenging water conditions, especially in water with low silica, total dissolved solids (TDS), and hardness.
Greensand-plus does not require potassium permanganate, but it does require one feed of chlorine ahead of the greensand-plus filter. If you are planning on using a chlorination system or a chlorinator, we usually recommend greensand-plus iron filters. If you don’t plan to chlorinate (or use ozone) ahead of the filter system, the regular greensand filter works better. In fact, Greensand Plus offers higher temperature tolerance and longer run times compared to traditional manganese greensand, making it a superior choice in many applications.
5. Do Greensand filters have any special conditions in order to work properly?
Yes! There are very specific conditions required. The water must have a pH of 6.7 to 8.8. If the water has a pH of less than 6.8 we usually recommend treating the water first with a neutralizer filter or a soda ash feeder. The best applications have feed or raw water of less than 15 PPM of iron and manganese, combined. The maximum practical removal rate for hydrogen sulfide is 5 PPM. The water should contain no tannins or oil.
Operating outside these pH and pressure ranges can cause damage to the greensand media, reducing its effectiveness and lifespan.
6. My water has a very bad smell of sulfur. Will this be removed?
While these greensand filters will remove up to 5 PPM of hydrogen sulfide, in some cases, the odor can come from conditions that exist after the water enters the plumbing. For instance, water heaters often have decaying anode rods that create hydrogen sulfide gas, so even if the water entering the water heater is clean and odor-free, you can still have an odor problem.
It is important to identify the source of the odor and to verify that it is in the cold water also, which would indicate that all the incoming water has an odor. In many cases, a thorough sanitizing of the household plumbing with chlorine is recommended after installation.
7. If I want to use a chlorinator for my water, can I use this type of iron filter?
Yes. These iron filters actually work better with a chlorine feed. With chlorine pretreatment, permanganate is not usually required.
8. I would like to use the Greensand-Plus or Greensand filter, with a chlorine injection system, but I don’t want chlorine in my house. What can I do?
You can use a backwashing carbon filter after the Greensand filter to remove all chlorine before it enters the house.
9. I have very high manganese (greater than .05 PPM), will these iron filters remove manganese also?
Yes, these systems work great to remove manganese, both dissolved and oxidized. For manganese removal, the Greensand filters are an excellent option, as many iron filters do a good job of removing iron but do not do a good job at removing manganese. Pro-OX filters also remove manganese however and do not need or use potassium permanganate.
10. What Maintenance Do Greensand Filters Require?
Every one to three months—depending on how often the iron filter backwashes—you need to add a few pounds of dry potassium permanganate powder to the solution tank. Once a year, set aside about an hour to perform general maintenance on the iron filter and permanganate solution tank. You won’t need any special tools. Performing regular maintenance ensures the system continues operating effectively and prevents any decline in performance.
11. How frequently do I have to replace the greensand filter media?
The filter media will last for 4 to 8 years, depending on usage and conditions. It is easily replaced.
