Comparing RO Membranes: Filmtec vs Hydranautics vs LG NanoH2O for SWRO

The SWRO Membrane Market Today

Three brands dominate seawater reverse osmosis membrane selection: DuPont Filmtec, Hydranautics (a Nitto Group company), and LG Chem's LG NanoH2O. There are credible alternatives from Toray, Suez, and a handful of regional manufacturers, but in nearly every project bid sheet we see at ForeverPure, the three majors anchor the membrane decision. They share a common form factor — the 8-inch × 40-inch spiral-wound polyamide thin-film composite element — and they overlap heavily in operating envelope. The differences that matter are in active membrane area, fouling resistance, salt rejection at the operating point you actually need, and lead time.

This guide compares them the way a practicing water treatment engineer would think about them — not by marketing claims, but by what the data sheets say and how the elements perform after 18 months in a real plant.

Filmtec SW30 Family (DuPont)

Filmtec traces back to Dow Chemical's pioneering polyamide TFC work in the 1980s. The product line has changed hands — Dow Water & Process Solutions became DuPont Water Solutions in 2019 — but the manufacturing pedigree and the spec sheets have remained essentially continuous. The SW30 series is the broadest and most widely deployed SWRO membrane family in the world. Notable models on the current catalog:

• SW30HRLE-440i — High-rejection, low-energy 440 ft² element with iLEC interlocking endcaps. The workhorse for high-rejection plants where energy efficiency also matters. Salt rejection nominal 99.8%, permeate flow ~9,000 GPD at standard test conditions (32,000 mg/L NaCl, 800 psi, 8% recovery, 25 °C).
• SW30XHR-440i — Extra-high rejection variant for ultra-low boron and chloride permeate requirements. Rejection 99.82%, lower permeate flow than HRLE.
• SW30HRLE-370/34i — Compact 370 ft² element on a 34-mil feed spacer. Used where pressure vessel housings are already in place from older systems.
• Seamaxx-440 — The Filmtec low-energy specification. Optimized for lower flux and lower operating pressure. Trades a small amount of rejection for a meaningful reduction in specific energy.

The iLEC interlocking endcap is a Filmtec-specific feature that mechanically locks adjacent elements together inside the pressure vessel, eliminating the conventional interconnector and significantly reducing the number of O-rings (and therefore the leak count) inside a typical 7-element vessel. iLEC is a strong reason to specify Filmtec when retrofitting older trains with seal failures.

See full product details on our Filmtec page.

Hydranautics SWC Family (Nitto Group)

Hydranautics is the membrane division of Nitto Denko Corporation, Japan, with US manufacturing in Oceanside, California. The SWC (SeaWater Composite) series has been the second-place global SWRO membrane for two decades and the first-place choice in many Asian and Middle Eastern projects. Current generations of note:

• SWC4 B Max — High-rejection / high-flow seawater element. 400 ft² active area. Salt rejection 99.8% nominal, boron rejection ~93%. Targeted at applications where boron compliance is critical (Mediterranean and Middle East seawater).
• SWC5 LD — The "Low Differential pressure" variant. The LD feed spacer is a thicker, more open mesh that resists biofouling and particulate accumulation, drastically reducing the rate at which pressure drop builds across the array between cleanings. The trade-off is slightly lower packing density. SWC5 LD is the go-to spec for seawater intakes with high biological activity or marginal pretreatment.
• SWC6 MAX — The current highest-area element from Hydranautics, around 440 ft². Combines high active area with the same high-rejection chemistry.

Hydranautics' historical strength is fouling resistance and cleanability. Their CIP recovery data — permeate flow restoration after standard alkaline and acidic cleans — consistently leads the industry. In open-intake plants where biofouling is the dominant failure mode, this matters more than the last 0.05% of nominal salt rejection.

See our Hydranautics page.

LG NanoH2O Family

LG NanoH2O is the newest serious entrant. The product is a polyamide TFC membrane with engineered nanoparticles embedded in the active layer — the Thin Film Nanocomposite (TFN) architecture LG acquired in 2014. The nanoparticles create additional preferred water transport pathways through the polyamide matrix, allowing meaningfully higher permeate flow at lower pressure without sacrificing rejection.

• SW 440 ES — Energy-saving variant. Highest permeate flow per element in its class.
• SW 440 R — High-rejection variant. Lower flow, higher rejection. Targeted at boron-critical applications.
• SW 400 SR — Compact 400 ft² element for retrofit applications.

LG's published performance numbers consistently lead the category on permeate flow and on combined flow-plus-rejection. The trade-off has historically been availability and the slightly higher unit cost; both have improved markedly over the past three years. See our LG membranes page.

Side-by-Side Performance

Representative high-rejection 440 ft² SWRO elements from each manufacturer, at standard test conditions (32,000 mg/L NaCl, 800 psi, 8% recovery, 25 °C, pH 8):

The numbers above are within manufacturer test tolerance of each other on rejection. The real differentiation shows up in operating conditions away from the test point and over the 5–7 year membrane life.

Fouling Resistance: LD vs Eco vs Standard

For any plant with open seawater intake — meaning, virtually any plant that is not on a beach well or a deep-intake system — fouling resistance dominates the lifecycle economics of the membrane. Three approaches in the market:

• Hydranautics LD (Low Differential). A 34-mil feed spacer instead of the standard 28-mil. Wider channels, lower particulate retention, slower pressure-drop rise between CIP cycles. Best in class for biofouling resistance.
• Filmtec Fortilife (formerly "Eco" branding). A surface chemistry modification that reduces biofilm adhesion. Helpful but less dramatic than the LD spacer.
• Standard 28-mil construction. Higher packing density, more active area per pressure vessel, lower CapEx per m² of membrane. The right choice for closed intakes (beach wells, MMF + UF pretreatment) where biofouling is well-controlled by pretreatment.

The choice between LD and standard is fundamentally an OpEx/CapEx trade-off. LD typically costs 8–15% more per element but cuts CIP frequency in half and extends membrane life by 12–24 months in fouling-prone water.

Cost and Availability

Membrane pricing is heavily volume-dependent and changes more often than the data sheets do. As a rough indicator (2026 list-equivalent for high-rejection 440 ft² elements):

• Filmtec SW30HRLE-440i: Strongest stocking position in North America. Typically 4–8 week lead time on standard elements. Project quantities (>100 elements) usually 8–12 weeks.
• Hydranautics SWC5/SWC6: Strong stocking in Oceanside, CA. Typically 4–6 weeks. LD variants 6–10 weeks.
• LG NanoH2O: Improved lead times in 2025-2026. Currently 6–10 weeks for project quantities, with stocking improving year-over-year.

For actual current pricing on your specific quantity and model mix, please request a quote — spot prices vary by 10–20% inside any given quarter.

Use Case Selection

Pressure Vessels and Form Factor

All three brands ship in the standard 8″ × 40″ spiral-wound form factor and fit any FRP pressure vessel built to ASME PVHO or the equivalent regional standard (Codeline, Bekaert, Protec, etc.). A 7-element vessel rated for 1,200 psi at 49 °C accepts any of the three. The one significant compatibility consideration is the iLEC endcap on Filmtec elements — iLEC requires Filmtec or compatible interconnectors on both ends of every element in the vessel, so you cannot mix iLEC and conventional ATD elements in the same housing.

Pressure vessel housings, interconnectors, and end adapters are stocked separately by ForeverPure to match whichever membrane brand you select.

Bottom Line

There is no single "best" SWRO membrane. The right choice depends on your feed water, your permeate quality targets, your pretreatment design, and the supply-chain reality of your project schedule. For most projects we engineer at ForeverPure, the decision narrows down quickly: Filmtec SW30HRLE for balanced North American projects, Hydranautics SWC5 LD for open-intake plants with biofouling risk, and LG SW 440 ES where energy or cold-water performance dominates the spec.

For a project-specific recommendation, see our membrane brand pages: Filmtec, Hydranautics, LG NanoH2O, and our membrane care guide.