Two popular shower filters on the Swedish market – with completely different technologies. We compare them honestly.
Velluva uses vitamin C and ceramic balls. Nordisk Renhet uses calcium sulfite, KDF-55D, and GAC. For Swedish conditions (chlorinated, often hard water), calcium sulfite + KDF is the demonstrably stronger combination.
Two completely different technologies
Velluva and Nordisk Renhet represent two distinct philosophies in shower filtration. Velluva focuses on natural materials (vitamin C, ceramic balls) and markets itself to the conscious consumer. Nordisk Renhet focuses on chemical efficiency and documented performance.
Let's look at the technology behind both – and what research actually says.
Velluva: Vitamin C and ceramic balls
Velluva uses a cartridge with vitamin C (ascorbic acid) and ceramic mineral balls. Vitamin C reacts with chlorine in a redox reaction: Chlorine gas + Ascorbic acid → Dehydroascorbic acid + Chloride ions + Hydrochloric acid.
The advantage of vitamin C is that it is gentle on the skin and does not produce any harmful by-products. The reaction is fast and effective at room temperature.
The disadvantage: Vitamin C is continuously consumed on contact with chlorine. The cartridge's lifespan directly depends on the chlorine content in the water – higher chlorine = shorter replacement interval. Ceramic balls (often tourmaline or far-infrared) have limited scientific documentation for water purification.
Nordisk Renhet: Calcium sulfite + KDF-55D + GAC
Nordisk Renhet uses three filter materials in series: Calcium sulfite reacts with chlorine and chloramine to harmless sulfate ions and hydrochloric acid. KDF-55D (a copper-zinc alloy) removes chlorine, heavy metals, and reduces bacterial growth through a redox reaction. GAC (Granular Activated Carbon) removes organic impurities, improves taste, and captures any remaining particles.
Calcium sulfite is particularly well-documented for shower use. Unlike vitamin C, calcium sulfite reacts faster at higher temperatures – which is ideal for showering where the water is warm.
KDF-55D has a long history of documentation in water purification and is listed in the NSF/ANSI 42 standard for chlorine reduction. Nordisk Renhet's filter is specifically designed for Scandinavian water: hard and chlorinated.
The Swedish National Food Agency states that Swedish drinking water may contain a maximum of 0.5 mg/L free chlorine and that the guideline value for trihalomethanes (THM) is 0.03 mg/L. Swedish limit values are among the strictest in Europe.
Read the complete technical guide on calcium sulfite
Swedish National Food Agency: Drinking Water
Comparison: Technical differences
How to read the table: The table compares two filter technologies — not all filter materials. Velluva uses vitamin C + ceramic balls. Nordisk Renhet combines calcium sulfite, KDF-55D, and GAC in a triple-media configuration.
| Property | Velluva | Nordisk Renhet |
|---|---|---|
| Main technology | Vitamin C + Ceramic Balls | Calcium Sulfite + KDF-55D + GAC |
| Chlorine reduction | Good (volume-dependent) | High (independently tested) |
| Chloramine reduction | Limited | Yes (KDF-55D) |
| Heavy metal reduction | Limited | Yes (KDF-55D) |
| Heat resistance | Good | Excellent (CaSO3 increases reaction at high temp) |
| Replacement interval | 3–6 months | 6 months / 10,000 L |
| Price (SEK) | Approximately 600–900 | 990 kr (cartridge: 398 kr) |
| Certification | None specified | Designed for NSF/ANSI 42 |
Which one should you choose?
For Swedish conditions – hard, chlorinated water – the calcium sulfite + KDF combination is the more robust solution. It is specifically designed to handle the challenges posed by Swedish shower water.
Velluva is a good alternative for those who prefer natural materials and have less challenging water (lower chlorine content, softer water).
Both filter types are a big step forward compared to not filtering at all.
Frequently Asked Questions
Does Velluva remove chlorine?
Velluva uses vitamin C (ascorbic acid) to neutralize chlorine. This works through a reduction reaction: Chlorine + Vitamin C → Dehydroascorbic acid + Chloride. The reaction is effective, but vitamin C is consumed quickly and the cartridge needs to be replaced more often than with calcium sulfite-based filters.
Which filter is best for sensitive skin?
Both filter technologies can be effective for sensitive skin. Nordisk Renhet's triple-media design (calcium sulfite + KDF + GAC) addresses more potential irritants: chlorine, chloramine, heavy metals, and organic pollutants. Calcium sulfite is particularly well-documented for atopic eczema in dermatological literature.
Are there independent tests?
There are limited independent tests for the Swedish market. American NSF/ANSI tests (NSF/ANSI 42) are the most recognized standard for shower filters. KDF-55D and calcium sulfite are both listed in NSF standards. Vitamin C-based systems have less established test data in this standard.
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Nordisk Shower Water Filter
Calcium sulfite + KDF-55D + GAC. Designed for Scandinavian hard, chlorinated water.
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