Q. Why are these systems called "Birm" 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 do they 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. See a diagram of the Birm filters and learn more.


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 these filters have any special conditions to work properly?

A. Yes! The water should 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 40 or 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. My water is hard also, I am thinking of using a water softener with an iron filter. Is that a good approach to consider?
A. Absolutely. Many people use a Birm iron filter first in line, followed by a good quality water softener. The Birm filter will remove iron, and the softener will remove the hardness. Additionally, if your water has a small amount of manganese in it, the softener will remove the manganese along with the hardness.


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. I have read or heard that the air-injector type systems used with Birm can be used on water with hydrogen sulfide, is that correct?
A.Yes, if your water is low in hydrogen sulfide (less than 2.0 ppm) these filters will remove the sulfur odor. However, under some conditons, if the air-injector becomes clogged or needs servicing and there is no air-injection, the Birm media can quickly break down in the presence of the hydrogen sulfide. Hydrogen sulfide levels can vary over the seasons, and it is possible the levels could increase beyond the removal rate of these filters. Generally we don't recommend these air-injection Birm filters for sulfur odor removal unless the levels are very low.


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 20 ppm. If your water has over 2.0 ppm of iron, generally you will need to add an air-injection system of some kind, such as a venturi, compressor, or a storage tank with air bubbler system.


Q. Are these systems big electrical power users?

A. No. The control valve uses only about 15 watts of energy to run the timer and backwash valve.


Q. I have 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. If I use the air-injector type Birm filters, is there any maintenance required for the air-injector?
A. Yes. The air-injector, which is installed in the pipe after the well and before the pressure tank, draws in air as water flows through it. Eventually these air-injectors need to be cleaned of oxidized iron and manganese that may build up in the air-injector. It is a simple task to turn off the water, unscrew the air-injector from the pipe and clean with a mild acid or vinegar solution. This is typically required once or twice a year.


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. If an air-injector type is used, there is approximately a 10 to 15 psi drop through the air injector. Sometimes this can be overcome by adjusting the pressure switch on your well pump system to cut-in and cut-out at higher pressure to compensate for the pressure drop.


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 filter media?

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


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.