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:
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.