Sulfur Water Treatment Systems Compared: AIO, Chlorination, Carbon & Aeration

I get calls all the time from people whose local water treatment company recommended chemical injection for their iron and sulfur. Chemical injection works, and so does air injection. I don't sell the chemical kind, because it needs service every month and the chemical is an ongoing cost. Here is every way to take hydrogen sulfide out of well water, side by side, with a source for each number.

Every sulfur treatment method side by side

Most methods below work one of two ways: they turn the dissolved gas into solid sulfur that a filter can catch, or they let the gas escape into the air. Carbon soaks the gas up instead, until it is full. What changes is how much hydrogen sulfide each one can handle and what it needs around it.

A water softener is not on the list. It is not built to take hydrogen sulfide out; its resin can hold a little until the resin fouls, and the smell comes through. The long answer is in does a water softener remove sulfur smell. What each level smells like, and what it means for your family, is in what your hydrogen sulfide level means.

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How an air injection filter works

An air injection filter keeps a pocket of air at the top of the tank; the water passes through that air, the gas turns into tiny specks of sulfur, and the filter bed below catches them. Ours uses Katalox Light, a filter media that also catches iron and manganese, so one tank handles all three. It backwashes the specks down the drain. It ships set to backwash every day, and that can be set to less often.

Each size of our air injection filter is rated for up to 10 ppm of hydrogen sulfide, 30 ppm of iron and 15 ppm of manganese. It works best near pH 8. If yours is lower, send me your test before you order. If your test shows you need an acid neutralizer too, I'll tell you where it goes.

I told a caller with a bad sulfur odor and an ozone unit that wasn't keeping up: "It removes extremely high levels of sulfur, up to 10 parts per million, and it works extremely well. It's the only thing we use now for sulfur." It comes in four sizes, from the 1.5 cubic foot at $2,095 to the 3.5 at $3,295; all four are with our other sulfur filters. A buyer of the 2.5 wrote, "it seems to have removed all the unpleasant odors and staining from our water." (Robon S., March 2026, Verified buyer)

What ships with the filter

What ships: the tank (empty), the new Fleck 2510 AiQ control valve with its bypass valve, a fill funnel, and the Katalox Light in separate bags or boxes, which is loaded into the tank at install. Drain tubing is not included; your plumber sizes it. The box has little or no install guidance, so use our guide on how to install an iron filter, and text me with anything it doesn't answer.

Who should install the filter

I recommend having a plumber put it in: about 2 to 3 hours, and about $800. Plumbing it in is an inlet and an outlet. The part that takes planning is the drain line to a floor drain, standpipe or utility sink, with an air gap, plus an outlet near the tank for the valve. I'm a phone call away for your plumber. If you'd rather do it yourself, text me with any questions.

The Katalox Light lasts about 6 to 8 years. Then the tank is emptied and refilled with new Katalox Light, $325 per cubic foot. On a well, the order is the well tank, a 5 micron sediment cartridge, this filter, the softener, a carbon tank after the softener if you want one, and a UV light last. The reasons are in the right order for well water treatment.

How chlorine injection removes hydrogen sulfide

Chlorine injection feeds a measured dose of chlorine into the water, the chlorine turns the hydrogen sulfide into solid sulfur, and a filter catches it. Penn State calls this kind of treatment, oxidation, the most common way to remove hydrogen sulfide, and says chlorine can handle any level; it is most often used above 6 ppm.

The parts go in this order:

The University of Georgia's chart calls for about 2.2 ppm of chlorine for every 1 ppm of hydrogen sulfide. Stenner's chart uses 3 ppm of chlorine per ppm. Chlorine has one thing going for it: it also kills iron bacteria and the sulfur-reducing bacteria that make the gas (Georgia).

The catch is the upkeep. Penn State says chlorination systems "require significant maintenance": the solution tank has to be refilled, the filter backwashed, and the carbon replaced now and then. In my video I put it this way: "chemical injection is something you have to service on a monthly basis. You have to go down and fill the hopper with water. You have to add the chemical to the water, and it's an ongoing cost." When a caller asked me about a chlorine injection system for a beach house, I told him we don't use it because it's too labor-intensive: "It has to be perfect."

If you already have chlorine injection and put our filter in, the two get along. I told one caller with chlorine injection, "Chlorine doesn't hurt the performance of it. It actually can help it." I also told him that a lot of people who add the filter "actually end up removing the chlorine injection system".

What a Stenner pump does

Stenner makes peristaltic metering pumps: rollers squeeze a flexible tube to push a measured dose of chlorine or peroxide into the water line. That tube is the part that wears out. Stenner's manual calls the pump tube perishable and says to inspect it often for leaks and wear. The injection fitting, where the chemical enters the pipe, needs cleaning now and then too. Stenner's brochure says to wire the pump into the well pump circuit or pressure switch. Pulsafeeder's Pulsatron pumps do the same job with a solenoid-driven diaphragm instead of a tube. We don't sell either one.

My video on chemical injection starts at the part where I explain why I don't use it:

How hydrogen peroxide injection works

Hydrogen peroxide injection is the same setup as chlorine: a feed pump doses the peroxide, a retention tank gives it time to react, and a filter takes out what it knocks out of the water. Penn State calls hydrogen peroxide "an excellent oxidant for hydrogen sulfide" but says its use in private systems "has been limited".

Stenner's chart calls for about 1.5 ppm of hydrogen peroxide for each 1 ppm of hydrogen sulfide, where the same chart lists 3 ppm of chlorine, and it figures on a 7% peroxide solution. At 4 ppm of hydrogen sulfide, that is 6 ppm of peroxide, which works out to about 11 fluid ounces of 7% peroxide for every 1,000 gallons of water you use, plus a little more for the leftover amount Stenner says to keep in the water. The 11 ounces is my arithmetic from Stenner's figures.

The strength of the peroxide matters. ATSDR, the CDC's toxic substances agency, says 3% to 10% is household strength and over 30% is industrial, and that above 10% it is corrosive to the skin and can cause burns. One caller with iron bacteria had been through permanganate, then an aerator with chlorine, and now had 34% peroxide going in. He told me, "I'd really like to get away from the peroxide."

Another caller already had a peroxide system on a Fleck 2510 tank, with a tank he had to keep filling. I told him carbon would just absorb the peroxide, and that we don't use anything with chemicals "because it's an ongoing cost". Above 10 ppm, past what our filter is rated for, a peroxide or chlorine feed is the answer, and that is equipment we don't sell. Up to 10 ppm, the air injection filter does the job with no chemical to buy.

Carbon filters for a light smell

Carbon works when the smell is faint: Penn State puts the limit at less than about 1 ppm. Above that, as I say in my video, carbon "works for a while, but carbon absorbs the sulfur", and if there is iron in the water too, "it's gonna shorten the life of carbon." One caller had a carbon filter put in for the smell, and "it got rid of the smell for 6, 8 months, and then it slowly came back".

Catalytic carbon is a different carbon made to handle more, but it still has to backwash, and it needs at least 4 ppm of dissolved oxygen in the water and 3 to 5 minutes of contact time (Penn State, Georgia). For sulfur, I send people to the air injection filter instead of a backwashing carbon tank.

For a light smell, the carbon tanks are our Clack non-backwashing ones: the 1.5 cubic foot at $1,495 and the 2.5 cubic foot at $1,695. With an air injection filter, a carbon tank, if you want one, goes after the softener.

Aeration systems for well water

Aeration bubbles air through the water in a tank and vents the gas to the outdoors (Georgia). It adds no chemical, and Penn State says it is normally not used above about 2 ppm. Connecticut gives the same 2 ppm line.

The drawbacks, from the Georgia and Connecticut guides: it leaves a strong rotten egg odor near the unit, so it needs to vent away from living space. The air pocket in the tank can be lost. Aeration can make sulfur bacteria problems worse if the bacteria are not killed first, which is why some put a chlorinator ahead of it. A filter or carbon goes after it for what it leaves behind (Georgia, Connecticut), and Penn State recommends disinfecting aerated water. Penn State also says the purchase price is often higher than other options. We don't sell aeration systems.

Ozone filters for sulfur

Ozone is another way to turn the gas into solid sulfur (Penn State), and the Water Systems Council says ozone treatment works up to 10 ppm. That figure is for ozone treatment in general. We used to sell two ozone filters, Katalox Light air injection filters on a Clack-based valve with an Ozotech ozone generator, and we no longer carry them.

For sulfur, I recommend the standard air injection filter. It has no ozone generator, so it skips the yearly upkeep those units needed: once a year, the ozone cell was cleaned and its two small check valves were replaced. When a caller asked whether the system came with ozone injection, I told him, "it's not really necessary with the air injection."

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