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Resin for Water Softeners


In the process of water softening, hard water is ‘softened’ by switching calcium and magnesium minerals with elements such as sodium, thereby making water better for you and your home. 

The heart of the process of softening undergoes in the mineral tank. This tank is filled with small polystyrene beads that are also referred to as zeolites or resin. Without resin softening water wouldn’t even be possible.

Top 3 Best Water Softener Resins Compared

What is Water Softener Resin?

These Ion Exchange resin beads are the main component that is responsible for the water softening process. They are small spheres that are usually 0.3 to 1.2 mm in dimension. Polystyrene strands wrapped around in a crisscross structure combines with Divinylbenzene (DZB) that glues the resin, which in turn creates the resin beads. The pattern of how the resin looks is in chain links. Most water softeners use 8% crosslink resin while high-end softeners use 10%. The more links in the chain, the more durable it is.

How Does Resin for Water Softeners Work?

First, the hard water moves into the tank. And as it moves, calcium and magnesium ions move along with the resin. The crosslink structure of the resin contains negatively charged “exchange sites” that hold sodium ions in place. The positively charged calcium and magnesium ions will stick to these exchange sites on the resin beads. And while these ions stick to the beads, the sodium is eliminated from the bead and goes into the water supply. Once the resin is soaked with calcium and magnesium it then is forced to enter the regeneration cycle. This cycle starts with reversing the water flow to flush dirt out of the tank. Next, the concentrated sodium solution is carried from the brine tank to the mineral tank. The resin beads are then collected by the sodium solution which swaps the hard water components as they go down the drain. Lastly, excess brine is flushed off from the mineral tank and brine tank is replenished.

When Do You Replace the Resin?

Resin lifespan is dependent on a number of factors, such as the percent of the crosslink, chlorine damage, iron damage, and hydraulic shock among others. However, the average lifespan of a resin is 10 to 15 years while 8% crosslink resin will likely breakdown 2-10% per year. And as it does, the softener will be fragmented with ‘fines’ that plug up the system which may result in a pressure drop. When this happens, water pressure is prevented to pass through the resin tank. Therefore, your unit will lose its capacity and performance and carry out more regeneration cycles than usual. This frequent process eventually wastes water and salt supply.

Other reasons for resin replacement are algae growth contamination, unused resin that starts to wreak a foul smell, and presence of fine sand. But instead of recharging or using more salt and water during its failures to function, it is more advisable to replace the resin instead. It is costly trying to recharge the resin as you will need to use more quantities of salt and water every time it breaks down. So for a longer term performance, replacing the resin for water softener is the better option.