The Truth About Air Injection Iron Filters

It seems that these days everyone in the water treatment business is selling an air-injection iron filter.  They market these as “chemical-free iron filters” and some do work… at least for a few weeks or months, unless you have high iron.  Then they may fail sooner.  If you have “low to moderate” iron, they may work for a while, but many are doomed to failure in the long-term.  Maybe, I should have called this “WHY US WATER SYSTEMS DOES NOT SELL AIR INJECTION IRON FILTERS.” But, before we discuss why they are doomed, let me explain how they work:

  • Companies who build these “air-injection iron filters” utilize a water softener control which used a “nozzle and venturi” assembly (commonly called and “eductor” or “injector”) which creates a vacuum that is used to draw salt water (commonly called brine) into a media tank (usually containing cation-exchange softening resin);
  • Instead of resin in the tank, these companies utilize media like Birm, Filox, Katalox, Pyrolox or Catalytic Carbon which provide an area for iron to oxidize; and
  • Instead of brine, the water softener valve draws air (which contains oxygen) into the media tank where it oxidizes the iron (allegedly).

That’s how it works and it really sounds great, doesn’t it?  However, like anything it is not all 100% true.  In fact, it may not even be 50% true.  Here’s the problem: Air is about 20% oxygen.  100% oxygen is a wonderful oxidizer, but air is 20% of that.  If you had an oxygen concentrator, you could make 100% oxygen and the results would be amazing. But, that would add about $3,000 to every system and the cost would become prohibitive.  So, the reality of the situation is that any air injection system is delivering no more than 20% oxidizing capacity, unless you have 100% oxygen.

For the uninitiated, to remove iron, it has to be oxidized – 100% oxidized!  But how do you oxidize iron with just 20% oxygen?  The answer is that sometimes you can’t, but the amount of iron that needed to be oxidized and the oxidizer (oxygen) might not be sufficent, and therein lies the problem.  The iron is not fully oxidized and it forms a tremendous amount of “iron sludge.”  This sludge fouls the media, coats the surfaces and plugs the injector so that it can no longer draw air through its eductor.  Then, the iron that has accumulated in the media and internal parts (and plugged the injector) continues to build up.  The system is overwhelmed with iron sludge and ceases to work. If you think I am making this up, check out this picture that was taken in an actual application after one year on just 2 ppm of iron:

Huge amounts of iron sludge of gloves from distributor tube.

Here’s what happens, oxidizing iron with air containing about 20% oxygen leaves a great deal of iron sludge behind around the the top of the tank, the value and the distributor, as well as the media itself becomes overwhelmed by the sludge.  Within a few months, the eductor (injector) is plugged with iron sludge and the water softener control value quits drawing air.  It does nothing.  The iron continues to build up and soon thereafter, the system is overwhelmed.  Sometimes it simply shuts down from sludge and the flow is greatly impacted. Most of the time, you just start noticing iron stains and by the time you do something about it, it’s too late.

There’s one way to make sure your air injection system doesn’t stop working and that is to disassemble the valve every 3-6 months, clean the parts with chlorine or sodium hydrosulfite and sodium metabisulfite, being sure to clean the injector assembly so as to allow it to function properly. It’s probably a good idea to clean out the media with chlorine or sodium hydrosulfite and sodium metabisulfite as well.

Now, if that seems like a lot of work, it is.  So, some customers just add on a room and let their local water treatment company technician live there (OK, that’s just sarcasm, but you get my drift).

So, what is the solution?  It’s simple for us – we use H2O2 instead of Oxygen – It’s a much better oxidizer than oxygen and it doesn’t require that a service technician move in with you.  Hydrogen Peroxide works every time and since it is such  great oxidizer, it does not leave all that iron sludge to clean up and there are no injectors to plug.

We sell systems all over the world.  We sell direct and eliminate-the-middlemen, so we can’t send out a service tech everytime you have a problem.  I know that people are going to write in and say that they have an air-injection iron removal system and it works, but they don’t work enough of the time that we can promise it will remove the iron or sulfur.  We can make that promise with hydrogen peroxide.  It works EVERY TIME.  No kidding around.

Check out our inFusion Systems  if you want to eradicate iron and sulfur.

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This article has 21 Comments

  1. Mark-
    Nice analysis on a common problem. I appreciate your humor, too. But I am looking for a rust removal system for a well-sourced water supply (Florida coast) lawn irrigation application. The OXi-Gen Systemc will cost more than I am willing to spend. I guess I’ll have to resort to periodic power washing of the fence and house exterior unless you have another idea. Note: Well is not used for household use.

  2. Les,

    You have to weigh the cost and if it is too much, I get that! Frequently, the chemicals you have to use to clean off rust can have a deleterious effect on them…

  3. I bought one of these air injection systems (from US Water mind you) and my valve looked like the picture above in 8 months. By the time I called tech support they had discontinued the sales of air injection system for this very reason – a lot of customer call backs apparently. I was frustrated at first but came to understand the product did not fail, it simply required more maintenance than I was willing to give. To US Water’s credit they were quick to understand the situation and get me upgraded to peroxide injection for under $1,000. The change was quick and easy for anyone who can work with pex or copper. Haven’t had any problems since. First impressions on USWater – knowledgeable – helpful. Just wish I would have bought the peroxide system first time around and saved myself some time. Also to speak to your point about a higher pressure backwash… this would require upgrading a well pump for some folks and that is just a whole other can of worms. That wasn’t in the cards for me so peroxide injection was the most cost effective route in my case.

  4. The average family spend $200 to $300 a year on H2O2.

    If you area “glass half empty person” you might think that is just an unnecessary expense.

    But, if you are a “glass half full person” you might think that is a small price to pay for awesome water.

    It depends upon your perspective.

  5. Thanks for the informative blog. As always there are more than one way to skin a cat…I am here because I have been using air injection for years now, but it is not with out a fair bit of maintenance. Replacing media beds in my tanks is required about every 2 years. I’ve gone past 2 years, but then I have more to clean out. The system was originally designed such that the Venturi drew air before my preasure tank, it then went thru a coil of 100 feet of 1 inch water line (gave the air time to turn the iron into a solid), then into a filter bed. Within 2-3 years, the 100 feet of hose would almost become blocked completely. I Do not advise this nonsense. I am building a new home and want to come up with a better solution. Perhaps go with the peroxide injection or change out the 100 feet of hose with a holding tank of sorts that won’t clog, something similar to what Jorge used, just not aeration. Your thoughts..
    Also, I had a someone tell me they had iron problems in their well. They started dumping a pail of hydrogen peroxide down the well periodically, and that they can’t believe how good it works. My thoughts there are that all of that iron is now collecting on the bottom of the well. Can’t be a good thing??

  6. Pouring H2O2 down the well is counter-productive. That’s not how the process works.

    H2O2 is simply much better than O2 and don’t use that 100 foot coil.

    Maintenance is almost ZERO. The media typically gets replaced every 5 years or so.

    That said, you need a detailed water test, like this:

    Once we know exactly what is in the water, and at what levels and if there are competing contaminants, the we can tell you if H2O2 is right for you… or if there is a better solution.

  7. I am tired of maintaining my pressurized air injector system. It is placed right before the pressure tank. The rust filter is after the pressure tank. There is no water softener in the system. We have a farm well.

    Over 2 1/2 – 3 years the pressure tank, line from pressure tank to rust buster cylinder and ‘5 in 1’ media bed inside cylinder are all pretty much plugged. The house water flow decreases to the point where its only one tap at a time and nobody uses an outlet or toilet when someone’s in the shower. The backwash system is working fine. The system just sludges in over time.

    I would like to just go to a water softener only.

    My water specs are:
    25 Hardness / 3.6 ppm Iron / 7.5 pH / 930 ppm Total Dissolved Solids

    1) How many ppm of iron can a softener alone remove?
    2) Would a softener only ‘kill two birds with one stone’ — take care of the hardness AND iron?
    3) Is there any validity to the statement ‘a water softener’s salt discharge will eventually wreck your farm house’ septic tank by eating the concrete’?

    I appreciate any insight /comments you can provide.

  8. Salt does not harm concrete, unless it is expsed to it while frozen. In that case, it heats the surface and caused it to “pop.”

    There are plenty of companies who will sell you a water softener that removes iron too… at least they say that. The truth is: That is pure fiction! At the pH your water is, you will not do a very good job of continually removing your levels of iron. You need this before the softener:

    Feel free to call us at 800-608-8792 to get more info.

  9. When you have this air induction system is your water the color of milk? Culligan put one of these on my well and my water smalls bad and is the color of milk. They say that is normal. Is it

  10. I was thinking of getting an oxidation filtration system until I read your article. I have very hard water, a lot or iron and high alkalinity(9) which is leaving my plumbing and faucets with black build up inside. I also have the rotten egg smell (the smell decreased a bit by changing my water heater sacrificial anode). I have heard so much different advice that I am left completely overwhelmed! I followed the link for the equipment you suggested in a previous post but it is very expensive ( Any advice?

  11. If you want to eradicate iron and/or sulfur, it is doubtful that an air injection filter will do that… especially after a few weeks. It is expensive, but in my life, I have found that cheap things aren’t good and good things are not cheap. We usually have some type of sale in place which can save you a few hundred dollars.

  12. So I have a question? Doc!
    It appears we are injecting peroxide before the the filter head ! So all the iron particles that are treated still pass thru the head ,what stops these participles from fouling the workings in the head! Because it appears they get filtered out after the head! Curious!!Seems the complaint with other systems is the fouling of the equipment This seems to have not changed here! What makes the infusions head impervious to fouling ???
    Just asking Thanx!

  13. Fred,

    That’s a very good question. Hydrogen Peroxide is H2O2, while Oxygen is O2. When using oxygen alone, the oxidation process starts as soon as the oxygen touches the water. Oxidation immediately occurs in the “air space” in the tank. On the other hand, with a Hydrogen Peroxide system, there is no “air space” in the tank and the H2O2 needs a catalyst in order to oxidize the iron. That catalyst is the media. The iron is oxidized on the media and backwashed out. Additionally, do not forget that Hydrogen Peroxide is a better oxidizer than oxygen and since the oxidation does not occur in the “air chamber” there is virtually no fouling.

  14. Thanx
    So with my well! I have a cistern added, low (yield well)! I find I have a lot of already oxidized material in the cistern that material is ending up in my iron filter and softerner head tends to coat everything with brown red slippery material Have quite high manganese , .734 ml/litre a bit of .188 iron ml /litre, ph 7.5 So from the cistern to the iron filter the pipes and the iron filter tends to give issues getting slined up on a fairly regular basis ! Can’t seem to find a way around the issue !
    Any ideas on what A guy can do in this case???

  15. Hello,
    My softener is starting to allow more iron to pass through. Literally just started this last month. The first company we had out last week suggested the Nelson aio system with fleck backwashing system. I was told that with nightly backwashing the injector etc becoming clogged would not be an issue?

    Obviously, your article seems to state differently. So will this occur regardless? My current setup just has a regular whf I have to swap every 4-6 months due to this sludge already. I do not want to be trying to clean that hunk out.
    Besides the 200-300 average per year what is the difference in cost between the h2o2 system and the chemical free air version.

  16. I have a well at my cabin in Sevierville TN. We replaced the whole house water system with a new Culligan system 3 years ago when we purchased the property because of orange tinted water and stains. Culligan promised that there system would take care of the problem. Well, here we are with the same problem that has never been corrected and tons of money being spent on filters. We have a water softner and use both a 25 micron prefiler; 1 micron post filter and a 75 micron pre filter; 25 micron post filter. I need a solution. My cabin is an overnight rental and I need to stop the complaints about the water. Please help me. Will the peroxide system help or do I need to consult a well water company?

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