iSpring WSP-50SL Spin Down Sediment Filter with Siliphos

Name: iSpring WSP-50SL Spin Down Sediment Filter with Siliphos
Brand: iSpring
Price: 79.99 USD

Sediment filter · 20 GPM · Treats sediment · $80 at iSpring as of Oct 2026

The iSpring WSP-50SL is the WSP spin-down with a Siliphos polyphosphate cartridge added in the same clear housing, making it a two-in-one sediment pre-filter and scale inhibitor. The 50-micron 316L stainless screen (100, 200, 500 or 1000 micron selectable) flushes and reuses, while the Siliphos beads are meant to help prevent scale and corrosion in water heaters and plumbing. Siliphos is an inhibitor, not a softener, and the cartridge needs replacing every 3-6 months.

Flow is 20 GPM with a 100 psi maximum (lower than the WSP-50's 115 psi) and 40-100 F for indoor use. The head is lead-free brass with 1 in. MNPT and 3/4 in. FNPT threads, the flush-out valve has a garden-hose barb, and the body has passed a 500+ psi burst test. It measures 3.5 by 3.5 by 9 in. No NSF/ANSI certification is cited.

Price was $79.99 at ispringfilter.com as of Oct 2026 (regular price); a push-fit bundle is sold separately at a higher price. Warranty is iSpring's standard 1-year limited term, with 30-day money-back and lifetime tech support. Install is DIY.

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iSpring WSP-50SL Spin Down Sediment Filter with Siliphos well water sediment filter

Specifications

Verified 2026-10-06. Fields the manufacturer does not publish are marked “Not stated”.

iSpring WSP-50SL Spin Down Sediment Filter with Siliphos specifications
Model	WSP-50SL (listed as WSP-SL; 50 micron). Other mesh sizes 100/200/500/1000 micron selectable on the same listing.
Type	Sediment filter
Treats	Sediment; also scale and corrosion inhibition (Siliphos), rust, sand, dirt
Service flow	20 GPM20 GPM maximum per the WSP series manual (Ver.05/2025) and the product listing. Product page: '40-100F, 20-100 psi and for indoor use only'; the shared WSP/WSP-SL manual says 'Suitable pressure range: 20-90 psi'.
Micron rating	50 micron50-micron 316L stainless mesh; 100, 200, 500 or 1000 micron options on the same housing.
Capacity	Not statedScreen is flushable/reusable; Siliphos (polyphosphate) cartridge replacement recommended every 3-6 months.
Media / technology	316L stainless mesh screen plus Siliphos polyphosphate scale-inhibitor beads in clear housing
Stages	1
Connection	1 in. MNPT + 3/4 in. FNPT
Installation	DIYDouble-threaded 1 in. MNPT / 3/4 in. FNPT ends; flush-out valve with garden-hose barb; see-through housing. Indoor use.
Warranty	1-year manufacturer warrantyWSP series manual (covers WSP and WSP-SL): 'We provide a 30-day money back guarantee, a 1-year manufacturer warranty, and lifetime tech support'; registration via the Warranty Registration tab on the iSpring site.
Certifications	Not statedLead-free stated; no NSF/ANSI or other third-party certification is cited for this model on the product page or in the manual. The manual describes Siliphos as 'a glass-like Polyphosphate with Sodium, Calcium Magnesium and Silicate, formulated specifically for scale prevention'. WQA certified-product search (find.wqa.org) returned zero results for 'iSpring', 'iSpring Water', '123Filter', 'WGB32B' and 'RCC7AK' on 2026-10-06 (a control search for 'Culligan' returned listings). NSF certified-product database (info.nsf.org), searched 2026-10-06: Exact model not listed. The iSpring NSF/ANSI/CAN 372 listing (Facility: Haining, Zhejiang, China; "Plumbed-In[LL]") names WSP50ARJ, WSP50ARJ-BP, WSP50ARJ-E, WSP 50SL-ARJ, WSP 50SL-ARJ-BP and the 100/200/500 equivalents, with "[LL] Product conforms with lead content requirements for “lead free” plumbing". Plain WSP-50 / WSP-50SL are not named; do not treat the ARJ entries as covering this row without iSpring confirming.
Dimensions	3.5 x 3.5 x 9 in.
Weight	1 lb
Price	$80 at iSpring as of Oct 2026

Published features

2-in-1 spin-down sediment pre-filter and scale inhibitor
Siliphos helps prevent scale and corrosion in water heaters and plumbing
Flushable, reusable 50-micron 316L stainless screen
20 GPM flow
Lead-free brass, 500+ psi burst test
See-through housing

Pros and cons

Pros

Adds polyphosphate scale inhibition to a basic spin-down for about $10 more than the WSP-50
Same reusable stainless screen and dual-thread head

Cons

Siliphos is a scale inhibitor, not a softener; cartridge needs replacing every 3-6 months
100 psi max pressure (lower than the WSP-50's 115 psi)
1-year warranty

Our take

For about $10 more than the WSP-50, the WSP-50SL adds polyphosphate scale inhibition, which is worth it on a sandy well with mild hardness where a softener is not in the budget. Do not expect soft water: the hardness stays, and the Siliphos cartridge is a recurring cost every 3-6 months. If scale is a real problem, pair a plain spin-down with a softener instead.

Not sure it is the right size for your flow and your water test? Work through the sizing guide, or compare every system we cover on the best sediment filters for well water (2026) list.

Where to buy

$80 at iSpring as of Oct 2026. Prices change; the links open the current listing.