Weddell Duo vs AquaBliss SF220: Which Inline Shower Filter?
Short answer: Pick the Weddell Duo if you want verified chlorine reduction: it is certified to NSF/ANSI 177 and removed all chlorine in independent testing. Pick the AquaBliss SF220 if budget comes first: it costs less upfront and lasts up to 6 months, but it is not NSF certified and we found no published independent chlorine test for it. Both are inline filters that keep your showerhead.
Head-to-Head
| Weddell Duo | AquaBliss SF220 | |
|---|---|---|
| NSF/ANSI 177 | Certified (chlorine) | Not listed |
| Independent chlorine test | 1.68 PPM to 0 (Water Filter Guru) | None published that we found |
| Filter media | Sediment prefilter plus carbon block | Redox media, activated carbon, calcium sulfite (brand) |
| Replace | 5 to 6 months / 8,000 gallons | Up to 6 months / 10,000 gallons (brand) |
| Fit | Inline, keeps showerhead | Inline, 1/2 inch thread, keeps showerhead |
| Price | $$ (about $90 list) | $ (under $50) |
| Looks | Horizontal cylinder; black, white, pink | Compact chrome cylinder |
| Best for | Certified results, eczema-prone or chlorine-sensitive skin | Lowest cost, renters, first filter |
The Big Difference: Verification
On paper, both use media that reduce chlorine. The difference is proof. The Weddell Duo appears on NSF's NSF/ANSI 177 listing, meaning an independent certifier verified its chlorine claim, and an independent reviewer measured chlorine going from 1.68 PPM to zero. The AquaBliss SF220 is not on NSF's listing, and we could not find a published independent chlorine test for the SF220 specifically. That does not mean it does nothing; it means you are relying on the brand's claims.
Filter Media
The Weddell Duo uses two stages: a sediment prefilter that catches particles and a carbon block. Carbon block filters are dense, which helps with chlorine and disinfection byproducts; in testing, the Duo reduced all four measured byproducts to zero.
AquaBliss describes the SF220 cartridge as a mix of redox media, activated carbon and calcium sulfite. Calcium sulfite is known for reducing chlorine, and redox media work through an oxidation-reduction reaction. A review of AquaBliss's sister model, the SF100, found it did little for disinfection byproducts, which that reviewer attributed to the lack of a solid carbon block.
Cost Over Time
AquaBliss is cheaper to buy, and its cartridges are rated for up to 6 months, so it is the lowest-cost way to try a shower filter. Water Filter Guru estimated the Weddell Duo's ongoing cost at about $72 a year. For many households, the yearly difference is modest compared to the value of verified performance. Larger households should check our filter life by household size table, since both brands' intervals assume typical use.
For Eczema and Sensitive Skin
If chlorine seems to bother your skin, choose the filter with verified chlorine reduction: the Weddell Duo. Keep expectations realistic: research links hard water, not chlorine alone, to eczema risk, and in a large trial a water softener did not improve existing childhood eczema beyond usual care. A shower filter does not soften water. Read hard water and skin for what the evidence shows.
Which Should You Buy?
- Weddell Duo if you want certified, tested chlorine reduction and do not mind paying more. Read our Weddell Duo review.
- AquaBliss SF220 if you want to try a shower filter cheaply, are renting, or only want a modest improvement. Read our AquaBliss review.
- Neither if your city uses chloramine (look for a filter designed for it) or your problem is hard water minerals (use a chelating shampoo or softener).
Installation Compared
Installation is nearly identical. Unscrew your showerhead, wrap the shower arm threads with plumber's tape, screw on the filter, then reattach your showerhead to the filter's outlet. Neither needs tools beyond your hands for most setups. The main practical difference is size: the Weddell Duo's horizontal housing is larger, so check clearance if your shower arm is short or your showerhead is close to the wall. The AquaBliss is a smaller, upright chrome cylinder.
Which One for Your Situation
| Your Situation | Better Pick |
|---|---|
| Chlorine-sensitive skin, eczema in the family | Weddell Duo (verified chlorine reduction) |
| Renting, want a cheap first try | AquaBliss SF220 |
| Four or more people sharing a shower | Either, replaced more often; compare cartridge prices |
| Love your rain or handheld showerhead | Either; both are inline |
| Want proof it works | Weddell Duo, or test either with chlorine strips |
| Short shower arm, tight space | AquaBliss (smaller housing) |
| City uses chloramine | Neither is certified for it; manage expectations |
| Hard water is the real problem | Neither; use a chelating shampoo or softener |
Check Either One Yourself
Whichever you buy, you can confirm it works with chlorine test strips: test water from the bath tap, then water through the shower, at the same temperature. A working filter shows a clearly lower reading. Retest every month or so; when the readings match, change the cartridge. Full steps are in our at-home shower filter test.
Why Certification Matters for Shower Filters
Shower filters are an easy product to oversell. Nearly every brand claims to remove chlorine, heavy metals and more, and almost none publish independent test data. NSF/ANSI 177 certification means an accredited third party tested the filter's chlorine reduction claim over its rated life and lists the exact product and replacement cartridge. Independent tests by reviewers have shown that marketing claims and results can be very different: one popular filtered showerhead showed no measurable chlorine reduction at all in testing. Certification does not guarantee a filter will fix your hair or skin, but it does tell you the core claim, chlorine reduction, has been checked by someone other than the seller.
Frequently Asked Questions
For verified performance, yes. The Weddell Duo is NSF/ANSI 177 certified and removed all chlorine in independent testing. AquaBliss is cheaper but not certified, and we found no published independent chlorine test for the SF220.
No. The AquaBliss SF220 was not on NSF's NSF/ANSI 177 listing when we checked in October 2026.
They are similar. Weddell says 5 to 6 months or 8,000 gallons; AquaBliss says up to 6 months or 10,000 gallons for the SF220.
If chlorine bothers your skin, the Weddell Duo has verified chlorine reduction. Neither softens water, and research has not shown that shower filters or softeners treat existing eczema.
Both are inline filters that fit standard US 1/2 inch shower arms and keep your existing showerhead.
Both are inline filters for a fixed shower arm. Your handheld or showerhead attaches after the filter, as long as it connects at the shower arm and there is enough clearance.
Yes. Compare chlorine test strip readings from the bath tap and from the shower through the filter. A working filter shows a clearly lower reading.
Yes. Both install the same way between the shower arm and your showerhead, so you can unscrew one and put on the other in a few minutes. Keep some plumber's tape on hand for the threads.
Last updated: October 2026. Sources: Water Filter Guru Weddell Duo review; NSF/ANSI 177 listing; AquaBliss product information.