What’s the Difference Between Fine Mesh Resin and Standard Resin When Removing Iron?

What's the Difference Between Fine Mesh Softener Resin and Standard Resin When Removing Iron?

Earlier this week, one of our customers asked about the difference between fine mesh and standard resin for removing iron with a water softener. We generally recommend an iron filter, but a water softener will do the trick in certain cases.

If your water’s pH is around 7.0, and your iron is rusted (ferric) and not clear (ferrous), you can indeed use a water softener for iron removal. For such applications, fine mesh resin is the more effective choice.

This is because fine mesh resin is smaller and packed more tightly than regular resin and has a larger surface area to which iron can attach. Under the right conditions, fine mesh resin can filter up to about 10 ppm of iron from water, though 5 ppm is generally a more realistic threshold.

While we recommend fine mesh resin for your softener if you intend to remove iron, we also want to note some drawbacks to using fine mesh resin.

To start, it is a bit more expensive than standard resin. Moreover, it can be fouled rather easily: if iron sits on the resin beads for too long (i.e., if the resin is not properly, regularly cleaned), it will begin to develop iron slime, at which point you’ll also need some resin cleaner. Iron oxide buildup is a common issue that can block resin exchange sites, reducing the system's capacity for softening.

Of course, this can also happen with standard resin, but it will occur more frequently with fine mesh resin due to its being more tightly packed. Note that such fouling will also reduce the effectiveness of your softener because the iron in the resin will limit cation exchange (the process by which softeners remove calcium and magnesium ions and replace them with sodium ions).

Whether you use standard resin or fine mesh resin, you may still experience fouling of your softener’s injectors when using it to remove iron. This is because the iron in your water is slowly oxidized by your softener as it sucks in brine from the salt tank through a small injector or venturi. When oxidized in this way, the iron can foul your injectors and necessitate more maintenance of the system.

However, these problems are not too critical. The injectors can be cleaned fairly easily, and you can avoid fouling your resin with iron by using an automatic resin cleaner feeder or by running your softener’s regeneration cycle frequently, perhaps every few days. Do note, though, that fine mesh resin will require more frequent backwashing than standard resin and thus will require more brine solution in the long run.

All in all, we recommend installing an iron filter before your softener for the absolute best results. However, if you want to stick with just the softener, fine mesh resin is definitely the better choice—just be sure to properly clean and maintain your system, and you should see that iron disappear in no time.

Visit our online store to browse our resin and other filter media. For more information about iron and water softeners, consult our free how-to guides.

Understanding Ion Exchange Resin

Ion exchange resin is a crucial component in water softeners, designed to remove dissolved minerals that cause water hardness. These resins are composed of tiny, spherical beads packed into a “bed” within the water softener tank. Each resin bead carries a negative charge, which attracts positively charged ions such as calcium and magnesium—common culprits in hard water.

The resin beads are pre-loaded with positively charged sodium ions. When hard water flows through the water softener tank, the resin beads attract and hold onto the hardness ions, releasing the sodium ions into the water in their place. This ion exchange process effectively softens the water by replacing the hardness ions with sodium ions, making it more suitable for household use.

How Water Softeners Use Resin

Water softeners utilize resin to effectively remove dissolved minerals from water supplies. Inside the water softener tank, the resin is arranged in a “bed” through which the water flows. As the water passes through this resin bed, the negatively charged resin beads attract and capture the positively charged hardness ions, such as calcium and magnesium.

During this process, the resin beads release sodium ions into the water, which replaces the captured hardness ions. This exchange softens the water and prevents the buildup of scale in plumbing fixtures and appliances. Over time, the resin beads become saturated with hardness ions and need to be regenerated. During regeneration, a brine solution flushes the resin bed, removing the captured minerals and recharging the beads with sodium ions, readying them for another cycle of softening.

Fine Mesh Resin vs Standard Resin

When choosing between fine mesh resin and standard resin for your water softener, it’s important to understand the differences and benefits of each. Fine mesh resin is composed of smaller, more tightly packed beads, which provide a greater surface area for ion exchange. This increased surface area makes fine mesh resin particularly effective at removing iron and other heavy metals from the water, in addition to the usual hardness ions.

On the other hand, while less expensive, standard resin is still highly effective at softening water by removing dissolved minerals. However, it may not be as efficient as fine mesh resin in dealing with iron. Fine mesh resin’s ability to handle higher concentrations of iron makes it a preferred choice for households dealing with iron-laden water, despite its higher cost and the need for more frequent maintenance.

By understanding your water softener system's specific needs and the characteristics of each type of resin, you can make an informed decision that ensures optimal performance and longevity of your water softener.