Where our numbers come from

One listing, one model

Each product page is one exact model. Its figures (grain capacity, resin volume, service flow, iron limit, bag weight, the parts a kit fits) are copied from that model's own listing, with the passage they came from kept on file.

When a listing doesn't give a figure, the page says “Not stated”. We don't fill gaps from a similar model.

When figures disagree

Listings sometimes print a number in the title and a different one in the specification table: a 48,000-grain title over a 32,000-grain table row, or carton dimensions where the tank size should be. Every specification is compared with the listing's own title and bullet points, and a row that contradicts them is left off the page.

The control valve

The valve on top of a softener decides how it regenerates and which parts fit it later. Where a listing names the valve (a Fleck 5600SXT, a Clack WS1, an Autotrol Logix) we show it on the card and the product page, and the valve-parts lookup lists every part whose listing names the same valve.

Softenry math

Our sizing tools show their formula and every input. The softener sizing works like this:

• Daily load: people at home × 75 gallons a day each × compensated hardness.
• Compensated hardness: your hardness in grains per gallon plus 4 for each ppm of ferrous iron.
• Weekly load: the daily load × the days between regenerations (7 by default).
• Usable capacity: grain ratings are full-salt figures; at an efficient salt setting a tank delivers about three quarters of its rating, so we use the rating × 0.75, or the resin volume × 24,000 grains per cubic foot when the volume is stated.
• Iron: up to 2 ppm any softener is listed; from 2 to 5 ppm only units whose maker states an iron rating at or above yours; above 5 ppm the tool sends you to iron filters first.

These rules follow published softener sizing guidance from university extension services and equipment makers. A unit is never listed as a fit below the weekly load.

Prices

Prices move daily. Product pages link to the seller, where the current price is shown; check it there before you buy.

Updated October 2026.