Iron comes in 3 different forms. The most common is what we call ferrous and ferric iron.
Ferrous is a clear water iron. It still stains (brown) as far as your fixtures, clothing, and dishware, if it is high enough, over 0.3 ppm or mg/L. Anything over that and iron will cause some sort of stain on your home.
If you let it sit into a container for a period of time with air in it it will oxidize and turn to a brown color.
That type of iron is called ferric iron (red water iron). So if the iron is high enough in your well, in a lot of cases, when you turn on a garden faucet and fill a container up, the water will have a discoloration to it which is caused by having ferric iron.
When you have ferric iron, there’s always a percentage of having ferrous iron mixed in with ferric iron. It’s not common at all to only have red water iron all by itself.
So you have to take that into consideration when you’re trying to put a recommendation together for a water treatment system to take care of it.
Where a lot of companies, people, technicians make their mistake by going out to jobsite to bid with their test kits.
They’ll do the iron test, read it right away, and mark it down. As an example, they’ll mark it down 2 ppm iron, not stating whether or not that is ferric iron or ferrous iron.
So where they’re making a mistake, is that your 1st reading is your ferric iron, your 2nd reading is your ferrous iron.
Once you take your sample and you read it right away and mark it down, as an example, 3 ppm of iron. That is your ferric iron, then you wait 5 minutes and you read again.
The difference between 2 ppm iron and the second reading of 5ppm is your ferrous iron.
So your total iron content combined is not 2 ppm (as 1st reading would say), which is where a lot of technicians make their mistakes. It’s actually 5 ppm, 2 ppm ferric iron and 2 ppm ferrous iron which changes your recommendation.
With that said if you have less than 3 ppm of total iron then your best course of action to treat that iron is a water softener using fine mesh resin.
If you have over 3ppm of iron, then your best course of action is to use a Katalox AIO Iron Master filter system and then follow that up with a water softener.
That way, you’re sure to remove all the iron from the water down below to .03ppm which is where the staining levels occur.
Article credit : Quality Water Treatment