Water Softener Resin & Filter Media

Resin & filter media · Buying guide

Water Softener Resin & Filter Media: Fix the Bed, Not the Whole Softener

Which water softener resin do you need?

Match the resin to your water source. Standard 8% crosslink resin suits most softeners. Choose 10% crosslink for chlorinated or chloramine-treated city water, fine mesh for well water carrying iron, and SST-60 if you want to use less salt and water. Nitrate select resin is a separate, specialty resin.

All softening resin is cation exchange resin: beads that trade calcium and magnesium for sodium, then get recharged by brine during regeneration. The types differ in how they handle chlorine, iron and salt use. Here's how the five compare:

A note on nitrate: Nebraska Extension notes that standard water softeners don't remove it, and the EPA limit for nitrate-nitrogen in public water is 10 mg/L. Get a lab test, talk to a water professional before ordering, and see our nitrate removal options.

How do you tell water softener resin is failing?

Watch the salt. If the softener uses salt at its usual rate but the water is still hard, the resin is probably worn out, iron-fouled or chlorine-damaged. If the salt level barely moves, the resin isn't being recharged, so the valve, injector or brine tank is the likelier cause.

On city water, chlorine slowly swells the beads until they break into fines that cut pressure or show up in aerators. On well water, iron coats the beads, so soft water runs out sooner. Match the symptom to the cause before you buy:

How much resin or media should you buy?

Buy the volume your tank already holds. Check the softener's label, manual or grain rating. By common industry convention, a softener holds about one cubic foot of resin per 32,000 grains of rated capacity, so a 32,000-grain unit takes about 1.0 cu ft and a 48,000-grain unit about 1.5 cu ft.

If you only know the tank size, use the typical volumes below (they match our GreenSand tank sizes). Never fill a tank to the top: the bed needs open space, called freeboard, to lift and clean during backwash.

Our resin comes in 0.75 to 3.0 cu ft sizes, depending on type. Between sizes? Call 866-278-4130 with your tank size and we'll check it.

How do you rebed a water softener?

Rebedding means emptying the old resin out of the tank and pouring in new resin. Most handy homeowners can do it in an afternoon with a funnel, tape and a wet/dry vacuum. Bypass the softener, pull the valve, remove the old resin, cap the distributor tube, add the new resin, then reassemble and regenerate.

1. Bypass and depressurize. Bypass and unplug the softener, then briefly start a manual regeneration to bleed off pressure.
2. Remove the valve. Disconnect the drain and brine lines, unscrew the valve and keep the O-rings in order.
3. Empty the tank. Use a shop vac or tip the tank over a tub. Spilled resin is as slippery as marbles.
4. Inspect the distributor tube. If beads reached your faucets, replace it while the tank is empty.
5. Cap and fill. Tape the tube top, pour any gravel first, then add resin through a funnel.
6. Reassemble and regenerate. Reseat the valve, restore water slowly and run a regeneration to rinse the bed.

Filter media goes in the same way. With calcite, leave 10 to 12 inches of space at the top.

Which iron filter media fits your water: Birm, GreenSand or Katalox Light?

All three remove iron and manganese in a backwashing filter, but they need different water conditions. Birm needs no chemicals but needs oxygen and a pH of 7.0 or higher. GreenSand also handles hydrogen sulfide but needs potassium permanganate. Katalox Light covers iron, manganese and hydrogen sulfide and lasts longest.

Your pH, any rotten-egg smell and your tolerance for maintenance decide it. Here's how they compare on each product's operating specs:

Birm needs dissolved oxygen of at least 15% of the iron or manganese content, so wells 50 feet or deeper usually need an air injector ahead of it. Katalox Light also filters down to 3 microns. Not sure what your tank was built around? Call us before you reload it.

What do calcite, Corosex, catalytic carbon and bedding gravel do?

These media handle the jobs resin and iron media can't. Calcite and Corosex raise the pH of acidic water. Catalytic carbon reduces chlorine, chloramine, VOCs, and bad tastes and odors. Bedding gravel sits under the media bed and spreads the flow evenly during service and backwash.

Calcite dissolves slowly into acidic water and raises its pH toward neutral. It stops dissolving once the water is neutral, so it doesn't overcorrect. Because it gets used up, top it up when the tank is about half full. A family of four uses about one bag every six months.

Corosex is a pH-raising media that's blended with calcite rather than used alone. Our listing pairs one 0.25 cu ft bag (30 lbs) with 1.5 cu ft of calcite, a 20% mix. Ask us whether your water test calls for the blend.

Catalytic carbon is activated carbon modified to be more reactive, which suits it to chloramine-treated city water. It fits whole-house carbon filters and won't remove hardness.

Bedding gravel supports filter beds and some larger softener beds. We suggest 3-inch layers. Many softener tanks 12 inches wide or narrower run fine without it.

What should you check before ordering resin or media?

Check four things before you order: your water source, a recent water test, your tank size and what the tank was built to hold. Get these right and the new bed fits, regenerates properly and treats the problem you actually have, not just the symptom you can see.

• Water source. City water with chlorine or chloramine points to 10% crosslink. Well water with iron points to fine mesh.
• A current water test. Know your hardness, iron, manganese, pH and any sulfur smell. A well water test kit covers the basics. For nitrate or bacteria, use a certified lab.
• Tank size and current volume. Measure the diameter and height, or read the grain rating, and order the same volume.
• What the tank was built for. Birm, GreenSand and Katalox Light need a backwashing filter valve. GreenSand also needs a permanganate feed. Don't swap media types without checking the valve.
• Parts and supplies. Replace a cracked distributor tube or worn O-rings while the tank is open, and have a funnel, tape and a shop vac ready.

When is new resin or media the wrong fix?

New resin won't fix a broken valve, a cracked tank or water problems the softener was never built for. If the control valve is failing, the softener is 15 or more years old and wearing out, or your test shows iron, acidity or nitrate, fix that first. Otherwise a fresh bed just fails again.

A rebed makes sense when the resin is the only worn part. If the valve skips regenerations, price a replacement control valve or a new softener from our SoftPro water softeners before you spend money on media. Heavy iron needs an iron filter ahead of the softener. Acidic water needs a pH neutralizer. For chlorine taste on city water, use a whole-house carbon filter.

USGS found about one in five sampled domestic wells had a contaminant above a human-health benchmark, most often inorganics such as metals and nitrate. If you suspect nitrate, use a certified lab, review results with a professional and re-test after treatment.

How we built this guide: Regulatory and prevalence figures come from the U.S. Geological Survey (private wells, well water quality and hardness ranges), the U.S. Environmental Protection Agency (secondary drinking water standards under 40 CFR 143.3, and chloramine use) and University of Nebraska–Lincoln Extension (nitrate). Resin and media details come from Quality Water Treatment's published product specs. Tank volumes are typical values, so confirm against your system.

Water Softener Resin: FAQ

Related: Iron filters · pH neutralizers · Whole-house water filters · SoftPro water softeners · Control valves · Brine tanks · Nitrate removal systems · Water test kits