Pros and Cons of Air Injection Filters-You better try Terminox®

Air Injector for well water iron filter systems
Air Injector ads air into the water which can introduce  bacteria/organics into the water line. Terminox®ISM iron and sulfur filters need no air injection.


The use of air injection in well water that has iron, sulfur, manganese etc. is very common. The main type of air injection filter we see is a filter designed to remove iron. Air is injected into the water line and then the air injected water goes into a tall thin filter tank that collects the sedimentary iron and periodically cleans itself of the iron sediment it has collected and sends it down the drain. You also see these filters to remove other unwanted substances such as sulfur and manganese. The downsides of a filter like this are:

Air is left in the treated well water: If air is in the water as it travels through the home, it can collect in any place that holds water. For example: if you use the water to shower the water brings air into the water tank. When the water stops after the shower there are millions of tiny air bubbles left in the water. These bubbles rise over time and leave a big air bubble in the top of the tank. This can be a lot of air over time that builds up. When the hot water is turned on again, the air can make the pipes “SPIT.” Most homeowners do not like pipes that spit hot water.

Iron Bacteria

Air injection iron filters and sulfur filters are susceptible to iron bacteria. To treat the water that contains iron bacteria, you normally must chlorinate the water. Air injection type filters were never originally designed to remove chlorine so now you must add an additional filter to remove chlorine. That makes this filter outdated technology. The most modern filters, such as Terminox ISM®, oxidize naturally and need no air injection. They also greatly reduce or remove leftover chlorine from the iron bacteria control process.

pH issues: You need a much higher pH water to remove both manganese and iron when both are present in the water supply. Usually it is recommended to have a pH of at lease 8.0 (or higher). The Terminox ISM® water filtration system can work (oxidize) at a much lower pH than 8.0 and is virtually maintenance free.

2 Comments on “Pros and Cons of Air Injection Filters-You better try Terminox®

    • While Terminox is more resistant to iron bacteria than any other well water filter, and we should know as we sell them all, that question is quite general. A lot depends on a variety of factors. Such as how much iron bacteria do you have? And another question would be what is your pH? If your pH is below 7.5 then iron bacteria is not the issue. It is the wrong question.

      Also, what size filter do you need? That is determined mostly by your flow rate. The larger the filter, the more likely it will be more resistant to iron bacteria. Terminox is superior in many ways to the old air injection technology. It works at lower pH ranges. It does not make hot water pipes “Spit”. It is far better at removing multiple contaminants. Such as iron, sulfur, manganese, chemicals, sediments, foul tastes etc. While we sell air injection filters, they are ancient technology at the residential level.

      Before you buy ANY iron filter from anyone, you should gather the information listed under items number 7, 16 and 17 on this page:

      You should never buy anything from anyone who does not require this information before determining what you need.

      We hope you find this information informative.


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