About Iron & Manganese Removal

General Iron Filter Questions

Q. How do iron filters work?

A.When your water is underground in your well, it is usually clear in color, even though it may contain high levels of iron. This is known as 'ferrous' or clear water iron. Iron filters take this clear iron and transform it to rust or ferric iron in the process known as oxidation. These trapped particles are periodically and automatically backwashed out to drain, usually once or twice a week. Most iron filters remove both clear water iron and ferric iron (rust).


Q. Which is the best iron filter for my application?

A. This depends on your well water chemistry. The first step is finding out if your cold water has a sulfur odor in it, or if it is just the hot water. If the water does have odor, then you need an iron filter that works in removing this sulfur odor, or you need to inject chlorine, ozone or hydrogen peroxide. The next step is to find out how much iron and manganese you have, and determine the pH (acidity or alkalinity) of your water. However you don't have to become a chemist in order to find out the simple parameters you need to know before selecting an iron filter. Click here for low cost accurate water analysis.


Q. Can't I just use a water softener?

A. Water softeners will remove dissolved clear water iron by a process known as ion-exchange. However, iron, manganese and/or hydrogen sulfide gas will eventually foul and ruin the ion-exchange resin. If your water contains less than 2.0 ppm of iron and manganese combined, and no sulfur odor, then you may be able to use a good quality water softener with a special type of resin cleaner in the brine tank. The resin cleaner will help clean the resin when the softener is being regenerated with the salt water. We don't recommend this approach however, its better to use an iron filter in front of the water softener for best results.


Greensand Filter Questions

Q. What are "greensand" iron filters?

A. These 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 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.


Q. How do they remove iron and manganese from water?

A. Iron and manganese are metals often found dissolved in water. They 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, and 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. 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.


Q. Is potassium permanganate toxic or harmful?

A. 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.


Q. What is the difference between "greensand filters" and "greensand-plus filters"?

A. The difference between GreensandPlus and manganese greensand is in the substrate that forms the core of the media and the method by which the manganese dioxide coating is attached to that substrate. GreensandPlus has a silica sand core and the coating is fused to it while Manganese Greensand has a glauconite core and the coating is ionically bound to it. The silica sand core of GreensandPlus allows it to better withstand operating conditions in waters that are low in silica, TDS and hardness.Greensand-plus does not require potassium permanganate, but it does require one feed in chlorine ahead of the greensand-plus filter. If you are planning on using chlorination 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.


Q. Do these systems come in different sizes?

A. Yes. The size of the system is directly proportional to the flow rate of the water, in gallons per minute. The higher the flow, the larger the system required. Recommended backwash flow rates must be observed.


Q. Do these filters have any special conditions in order to work properly?

A. 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.


Q. My water has a very bad smell of sulfur, will this be removed?

A. While these greensand filters will remove up to 5 PPM of hydrogen sulfide, in some cases the odor can be coming 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 that 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. Also see our report on How To Treat Odors in Well Water.


Q. If I want to use a chlorinator for my water, can I use this type of iron filter?

A. Yes. These iron filters actually work better with a chlorine feed. With chlorine pretreatment, permanganate is not usually required.


Q. 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?

A. You can use a backwashing carbon filter after the Greensand filter to remove all chlorine before it enters the house.


Q. I have very high manganese (greater than .05 PPM), will these iron filters remove manganese also?

A. Yes, these systems work great to remove manganese, both dissolved and oxidized. For manganese removal these 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.


Q. What maintenance is required for the greensand filters?

A. Once every one to three months depending on how often the iron filter is set to backwash, a few pounds of dry potassium permanganate powder is added to the little solution tank. Once a year there is some general maintenance that should be done to the iron filter and permanganate solution tank, which takes about one hour. No special tools are required.


Q. Will there be a pressure drop through the system?

A. Properly sized, the system produces a very low pressure drop at service flow rates, usually around 5 psi. Most people don't see any pressure loss in their household piping.


Q. Can I route the backwash water to my septic tank?

A. Yes. The backwash water can be routed to the septic tank with no problem in almost all cases.


Q. How frequently do I have to replace the greensand filter media?

A. The filter media will last for 4 to 8 years depending on usage and conditions. It is easily replaced. Need more information? E-mail us: info@cleanwaterstore.com


Birm Iron Filter Questions

Q. What are "Birm Iron filters"?

A. Birm is a trademark name of the Clack Corp. These iron filters use a type of granular filter media called "Birm". It is manufactured from a type of natural pumice mineral coated with manganese oxide.


Q. How does Birm iron filters work?

A. As the water flows through the filter tank containing Birm media, a reaction occurs where the dissolved oxygen and the dissolved ferrous iron compounds form an insoluble ferric hydroxide. In plain English, as water containing iron flows through the media, if there is enough oxygen in the water, the Birm causes the iron to form rust, or solid iron particles. After these rust particles get trapped in the filter media, once or twice a week they are automatically backwashed out to drain, and the filter media is ready to filter again.


Q. Do these systems come in different sizes?

A. Yes. The size of the filter system is directly proportional to the flow rate of the water, in gallons per minute. The higher the flow rate, the larger the system required. See our table for the flow rates for Birm iron filters.


Q. Do Birm iron filters have any special conditions to work properly?

A. Yes! The water must have a pH of 7.0 to 9.0. In addition, the dissolved oxygen content must be at least 15% of the iron or manganese content. For most wells deeper than 50 feet, an air injector must be used to introduce some additional oxygen in the water prior to the Birm filter. If the water being filtered is water from an open storage tank or spring, no additional air injection is usually required.


Q. Anything else I should know about using a Birm iron filter?

A. Yes, the water should contain no tannins, chlorine, oil or hydrogen sulfide (rotten egg odor). For water with any of these items we recommend the greensand filter systems. A inexpensive water test of your raw well water is highly recommended before purchasing these systems.


Q. My water has a very bad smell of sulfur, is this a problem?

A. Yes. Do not use these iron filters when hydrogen sulfide (a natural toxic gas formed by iron and sulfur bacteria) is present. Depending on the levels of hydrogen sulfide gas, , it is better to use chlorination or ozone, followed by greensand or greensand blend iron filters if hydrogen sulfide and/or iron bacteria is present.


Q. If I chlorinate first, or use a chlorine bleach feeder for my well water, can I use this type of iron filter?

A. No. These iron filters should not be used if the water has a chlorine residual. De-chlorinate before the iron filter using a carbon filter, or better yet, use the greensand type of iron filter.


Q. How much iron will these Birm filters remove?

A. Generally up to 15 ppm under the right conditions.


Q. I have very high manganese (greater than .05 PPM), will these iron filters remove manganese also?

A. Generally we do not recommend Birm filters where manganese is present. For manganese removal to be effective, the pH must be between 8.2 and 9.0. It would be better to use a greensand filter to reduce manganese.


Q. What maintenance is required?

A. Under the right conditions there is little maintenance. This is the great advantage of the Birm filters. If you have water with a pH of 7.0 to 8.0, no odor or tannin present, and you are not using chlorine, Birm lasts for 5 to 10 years with little maintenance.In some cases depending on how hard the water is, the control valve backwash piston needs to be replaced every 3 to 5 years, but this is also easy to do by anyone. No special tools are required. The systems uses no salt or chemicals and there are no filter cartridges to replace.


Q. Is there a pressure loss through the system?

A. When properly sized, the system produces a very low pressure drop at service flow rates, usually around 5 psi.


Q. Can I route the backwash water to my septic tank?

A. Yes. The backwash water is non toxic and can be routed to the septic tank with no problem. It can also be routed to landscaping, although the backwash is usually very dark and orange, and will stain surfaces.


Q. How frequently do I have to replace the Birm filter media?

A. The filter media will last for 4 to 8 years depending on usage and conditions. It is easily replaced.


MangOX Iron Filter Questions

Q. What is MangOX?

A. MangOX is a trademarked name. A naturally mined ore, MangOX is a form of manganese dioxide which has been used in water treatment for more than 75 years. MangOX is a granular filtration media for hydrogen sulfide, iron and manganese reduction.MangOX functions as a catalyst, but itself remains relatively unchanged.


Q. How does it work?

A. MangOX works on a principle whereby the hydrogen sulfide, iron and manganese are oxidized and trapped on the media while simple backwashing cleans the bed. No chemical regeneration is required, nothing is imparted into the drinking water and MangOX has a high capacity for low contaminant concentrations. If there is odor present or iron bacteria, it works much better with a chlorine feed ahead of the iron filter.


Q. Can MangOX be used with aeration or chlorination?

A. Yes MangOX can be used in conjunction with aeration, chlorination, ozone or other pretreatment methods for difficult applications. Like with Greensand-Plus filter media, chlorine or other oxidants accelerate the catalytic reaction.


Q. What are the disadvantages of MangOX?

A. Because of its heavy weight, it is very important that MangOX filters are backwashed properly to insure adequate bed expansion and continued service life. For instance, a standard 1.5 cubic foot size Greensand or Birm iron filter, which is a typical size for a 2 or 3 bathroom home, needs 7.0 gallons per minute to backwash. A MangOX filter may take up 15 to 20 gallons per minute for the same filter.


Q. Can I get assistance in choosing an iron filter system for my application?

A. Yes! You should first have your water tested, and then contact our technical staff for help on selecting the best iron filter system for your application. Also see our Custom Water System Design Questionnaire which makes it easy to help you select a system.