Why You Should Never Buy an Air Injection Iron Filter

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 they do work… at least for a few weeks or months.  But they 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.

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 YOU DON’T 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 Oxigen – 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.  Check out our OXi-Gen Systems  if you want to eradicate iron and sulfur.

This article has 17 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. Jesus Christ you people should pay attention in high school chemistry class. Does does the O2 (actually 21%) O2 in the eductor limit the reaction of the iron? How so? Just because it’s not “A FULL 100%” doesn’t mean it limits the oxidation reaction because of insufficient reactants. You just don’t KNOW without a proper test. And a clogged eductor would mean the dissolved iron would NOT be oxidized and would instead make it’s way through to the softener (if it exists) or to the faucet / toilet. THERE it would be oxidized as a red precipitate that you call the “sludge”. The real problem with air injection systems is insufficient backwash pressure to flush the oxidized “sludge” to the drain. And yes, if it gets to the catastrophic level your picture apparently shows your delivered water rate would have been terrible for a long time. Size the system correctly and set the recharge frequency correctly and this isn’t a problem for at least 5-10 years at a time.

    Jesus, you con artists are disgusting. I’ll bet you call this “capitalism”. I’ll bet you voted for Trump as well. Idiot and liar.

  4. I am allowing this to be published to let people see how moronic some people are.

    You have no clue and apparently your reading skills are wanting.

    Move on… there’s nothing to see here, Folks.

  5. it sounds like the response from the chemist makes sense. i think, that you should elaborate on his response. thats the business way of doing things, not mockery. is there a backwash procedure for this item. if so, then thats the purpose of the backwash, to get rid of the sludge. so maybe its true that it wasn’t sized correctly, to effectively to its job. first, i never heard anything bad about the air injection systems. second, its like 90% of the country, who uses it, has it.

  6. James,

    How many air injection systems have you installed?

    The “Chemist” has a pompous grandiose elevated opinion of himself, but I wonder how many he has installed all well.

    They sounded good to us and we installed “hundreds of them.”

    In reality, it is a bad idea… unless you are really adept at cleaning the valve and the top of the tanks where the iron builds up a very thick sludge in a matter of weeks… not 5-10 years like the Chemist says, who has no experience at this whatsoever!

    Look, we wish that an air injection would work, but they are very problematic. That’s why we no longer sell them. Buy one and you will find out what we already know!

    Believe what you want – we have to sell equipment that works because we sell it all over the world. We have no vested reason NOT to sell air injection… except for the fact that it is VERY problematic. It works on paper!

  7. Chemist, 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.

  8. Can you please comment on the differing chemical reactions that are at play with these two different approaches to oxidation (complete oxidation with H2O2 and partial (?) oxidation in the case of air as the oxidizer) ? Why would air create sludge and H2O2 not create any?

  9. For two simple reasons:

    1. You simply do not have enough oxygen inside a tank to totally oxidize; and
    2. H2O2 is a dramatically better oxidizer than O2.

  10. The chemist may have chopped sentences but over all he is correct. Back washing is key to the system working. I use a commercial air injected system with an air compressor with seperate tank to oxidize and tanks after to filter the oxidized iron. We have been using system for 20 years with ZERO ppm iron after going thru the system.. I did have to refill the media removal material once and replace the air compressor 2 times, but other then that ZERO iron after system… ZERO clogging of any valves..

    You do not need 100% oxygen to oxidize iron,

  11. The headline mentions “5 Reasons” why you should never buy an air injection filter, but the article essentially covers one reason—sludge buildup. Am I missing something or could you enumerate the other 4 reasons?

    Aside from the headline I thought it was a very informative article, and kudos for allowing the dissenting opinions. I think a balanced debate is essential in determining the relative strength of each assertion. However, there is no reason for disrespecting someone if you don’t agree with them.

  12. Scott Is this your set up or was it provided by ?? I am interested in something similar that I can maintain without having a water treatment company live in the pump house. It is just iron .

  13. “Just iron?” Iron is one of the most troublesome elements on the face of the earth to get rid of.

    Air injection will work on low amounts and it also depends upon the type of iron. If it is bacterial in nature, you can forgetabout it.

    Do you know what your iron levels are? I have no clue what his are.

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