Shower filter, softener or both: chlorine versus hardness minerals

Short answer. Chlorine and hardness minerals are two different problems, and a shower filter that targets one does not touch the other. The maker of the filter we read says so on its own page. If your problem is scale, soap film or spotting, look at hardness. If it is a chlorine smell, look at a chlorine filter. If you have both, they are two separate jobs. We have not tested any of these products. This page gives information from the sources named, not medical or plumbing advice.

Two problems with two names

Hardness. The US Geological Survey (USGS) says water hardness is "generally the amount of dissolved calcium and magnesium in water". It describes the effects you notice: your hands feel slimy after washing with soap, or glasses become "less than crystal clear". It also says "When hard water is heated, such as in a home water heater, solid deposits of calcium carbonate can form." USGS adds: "Hardness is a property of water that is not a health concern, but it can be a nuisance."

Chlorine. We did not read a source on how much chlorine reaches your tap or why. What we read is what a filter maker says it targets. Frizzlife's K45-B page says its cartridge uses KDF-55 and calcium sulfite media "to help reduce free available chlorine" in shower water, and that "it does not remove hardness minerals such as calcium and magnesium, so it is not a water softener". Ask your water utility which disinfectant it uses and how hard the water is. Both are things they can tell you.

How hard is hard?

Four colored bands showing USGS water hardness classes: soft is 0 to 60 mg/L, moderately hard 61 to 120, hard 121 to 180 and very hard more than 180, all as calcium carbonate. — Source: USGS, Hardness of Water, read 2026-11-01. The last band is open-ended, so its length is not to scale.

Worked example, our arithmetic from the USGS bands: a utility report that gives 150 mg/L as calcium carbonate falls in the 121 to 180 band, which USGS calls hard. A report of 45 mg/L falls in the 0 to 60 band, which USGS calls soft. If your number is in the soft band, hardness is not what you are seeing, and a softener would not address a chlorine smell.

A decision tree

Decision tree: chlorine smell points to a shower filter that states chlorine reduction; white scale, spots or soap film points to a softener or scale conditioner; both are two separate jobs; not sure means get the hardness number first. — An illustration of the sorting step, built from the Frizzlife K45-B page and the USGS page, both read 2026-11-01. Not a test result.

What you notice	What it points to	What the sources say
Soap film, spotted glasses, white scale	Hardness	USGS ties these to dissolved calcium and magnesium. The K45-B page says it does not remove them.
Chlorine smell in a hot shower	Chlorine	The K45-B page says its cartridge helps reduce free available chlorine. It names no figures for how much.
Both	Two jobs	Treat hardness where the water enters or heats; add a chlorine filter if the smell bothers you. See our softener and filter guide.
Flaky or itchy scalp	Unknown	We found no source here that ties a shower filter to a scalp condition. Our hair guide reads the labels and the studies. A doctor or dermatologist is the person to ask about the scalp itself.

What a filter cannot do

A shower filter that reduces chlorine is not a softener. The K45-B page says so more than once.
The K45-B page says it is designed for a fixed head plus a handheld hose. It does not describe a version for a single head.
Frizzlife's pages say nothing about chloramine for the K45-B. If your utility uses chloramine, ask the seller whether the cartridge is claimed for it.
For how a softener is sized and what it needs, see our softener buying guide. Frizzlife's menu lists no softener, so there is no Frizzlife card for that half.

What the sources do not say

No source we read gives the chlorine level in your water or says what level a filter should cut it to.
USGS describes hardness in general. It does not say what a softener or filter does to hair or skin.
The K45-B page cites testing by SGS to NSF/ANSI 177 and says that is not NSF product certification. Our certification guide explains what to ask.

The cheaper or simpler option

Get the two numbers first. Your water utility can tell you the hardness and the disinfectant, usually at no cost. A test strip also works; our water test guide covers strips and lab kits. If hardness is the problem, a shower filter will not fix it, and the money belongs in a softener or conditioner. If the water is soft and you only smell chlorine, a filter is the right tool. If a new head is what you want, see our showerhead guide.

If chlorine is the problem

Our reason to click: the K45-B page states in its own text what the cartridge reduces and that it does not soften, so you can match it to the problem you measured.

We earn a small commission on qualifying sales, and 90% of it goes to charity (you can pick which); your price is unchanged. Full disclosure.

K45-B shower filterDual-outlet filter only, no shower heads. The page states up to three months of cartridge life.View at Frizzlife →K45 filter and shower bundlesThe collection page lists the filter alone and with handheld or fixed heads.View at Frizzlife →

Sources

USGS: Hardness of Water, read 2026-11-01.
Frizzlife K45-B product page and the shower collection, read 2026-11-01. Maker claims.

The Frizzlife links on this page are affiliate links. We earn a small commission on qualifying sales, and 90% of it goes to charity (you can pick which); your price is unchanged. Full disclosure.

Next steps

Replacement schedule worksheetStated filter lives side by side.Reading a certification claimWhat to ask before you pay.How to test your water at homeStrips versus lab kits.