Birm, Greensand, and MangOX Iron Filters
The three most common systems available to remove iron from well water are backwashing iron filters that use one of three different media: Birm, Greensand, and MangOX (manganese Oxide such as Pro-OX).
Iron makes up 5% of the Planet’s crust and is found in well water throughout the world. Whenever the amount of iron in your well water is higher than 0.3 Milligrams Per Liter (mg/L) the water can have a rusty, red-colored, brownish, or even yellow color, and cause discoloration of fixtures as well as laundry. Metallic tastes will probably be present and the water may smell horrible.
Thankfully you can get easily find iron filters that will work great and remove the iron. However, it is important to select the best iron filter for the job, and the iron filter should be carefully chosen after a water analysis has been performed.
Test The Water and Find Out the Well Pump Flow Rate First
It is important to have the water analyzed for pH, general minerals and bacteria before choosing an iron filter. Besides analyzing the water, find out what your current well pump flow rates are, in gallons per minute so you can know that the iron filter you choose will work with the flow rate you have.
Birm is a trade name of the Clack Corp. The media is manufactured from natural pumice mineral which is then covered with a very thin layer of manganese dioxide. Birm only will work if there is adequate dissolved oxygen in the water. The oxygen acts as a catalyst to change the dissolved iron into a dense rust particle that the Birm can then remove. The iron rust contaminants become trapped in the Birm filter media and are then regularly removed by an automated backwashing of the iron filter.
Birm will not reliably remove manganese unless the pH is over 8.2 and is generally not recommended when manganese is present. It absolutely cannot be used in the presence of hydrogen sulfide gas or if chlorine is in the water.
Because most well waters are generally low in dissolved oxygen, some type of air compressor or air injector should be used to boost the oxygen in the water. Birm filter media will not take out iron when the pH in the well water is under 6.9. While lowest in cost, Birm doesn’t last that long and may need to be changed every few years.
Just like Birm, Greensand has a thin coating of manganese dioxide. However, Greensand does remove manganese as well as hydrogen sulfide odors. Greensand filter systems do not use air injection, but instead use a chemical known as potassium permanganate, a purple powder, to completely clean as well as restore the greensand filter media.
An alternative choice to potassium permanganate can be to inject some chlorine bleach upstream of the Greensand Filter which then allows the filter to remove iron bacteria, odors and enable the Greensand Filter to remove virtually all iron as well as manganese. Well water filters using greensand generally will remove greater levels of iron as well as work better when compared with Birm. This kind of iron filter works well right down to a pH of 6.5 but works better and lasts longer if the pH is in the range of 6.8 – 7.5.
Greensand’s advantage is that it is light weight and requires less backwash water, and is lower in cost than solid manganese oxide media filters (see below). It does need to be changed every few years though, and does not last as long as manganese oxide media.
Unlike Birm and Greensand, Manganese Oxide filters use a solid manganese oxide ore and therefore are not coated. Manganese Oxide Filter systems have brand names such as Pro-OX (our own brand, which is a high purity form), Pyrolox, Filox, Catalox, MangOX and other brands. This particular media will last many years longer than Birm or Greensand.
Because the media is extremely heavy it must be back-washed with a higher flow of water than Birm or Greensand. These types of well water filters work best when the water has been injected with chlorine bleach upstream of the iron filtration.
Manganese oxide filter will often work better than the other types of well water filters, as long as there is sufficiently higher backwash flow rate to properly clean the heavy filtration media. Manganese Oxide media can be utilized down to a pH of 6.2 theoretically, but work best if the pH is between 6.8 and 7.5. It is the longest lasting of these iron filter media and can easily last 10 to 15 years. We have some customers using the same manganese oxide media since the early 1990’s. In addition, to remove iron and manganese, this media will remove other metals such as arsenic under the right conditions.
For manganese oxide to work correctly, the ORP level (which can be easily measured) must be over 200. Depending on the application manganese oxide works great if air is injected, or the water is chlorinated or ozonated prior to the iron filter, which ensures the ORP level is high enough for the oxidation process to reliably occur.