2.5"x21" | 300 GPD | 99.6% Salt Rejection | Watermaker Seawater RO Membrane | Applied Membranes

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AMI 2.5x21 Seawater Desalination Reverse Osmosis Membranes
For Watermakers and Land-and-Sea Based Seawater Desalinators

Highest Salt Rejection Seawater RO Watermaker Membranes

AMI high rejection and high productivity seawater reverse osmosis membranes are specially designed for marine applications. AMI SWRO membranes are ideal for seawater desalination in shipboard applications, watermakers, land-based desalinators and sea-based desalinators.

AMI Membranes are Made in the USA in their ISO 9001:2015 Certified Facility and are 100% Quality and Performance Tested. 

Looking for a replacement seawater desalination membrane element for your watermaker filter system? View our Watermaker Replacement Membrane Chart.

Specifications for SWRO Membranes for Watermakers

Benefits of AMI Seawater Desalination RO Membranes:

  • Convert seawater into drinking water on yachts, boats, cruise ships, off-shore platforms, and resorts
  • High Rejection & Flow Rate 
  • Made in the USA 
  • Manufactured in ISO 9001:2015 Certified Facilities 
  • 100% Performance and Quality Tested 
  • High Quality for Consistent and Reliable Performance
  • Uses the most advanced membrane film technology and manufacturing processes
  • Industry Standard 2.5"x21" dimensions to fit in commonly available housings.
Genuine AMI Membranes ISO USA Quality

M-S2521A Specifications

AMI Model Number M-S2521A
Size (Approximate): 2.5" Dia. x 21"L
Flow Rate: 300 gpd (1.14 m³/d)
Applied Pressure: 800 psig (55 bar)
Stabilized Salt Rejection: 99.6%
Minimize Salt Rejection: 99.4%
Single ELement Recovery: 4%
Exterior: Hard Shell Fiberglass
Membrane Type:
Polyamide Thin-Film
Can Replace Models:

DOW SW30-2521
DuPont SW30-2521
FilmTec SW30-2521
Spectra FT-MB-20
Katadyn FT-MB-20
Most industry-Standard 2.5x21 Seawater RO Elements
For Use in Systems:

Watermakers or marine systems using 2.5x21 SWRO Membranes

Katadyn Spectra Systems:
Ventura 150, 150c
Ventura 200T, 200c
Catalina 340c Compact
Cape Horn Extreme 330 Compact
Newport 400c Compact
Aquifer 150
Aquifer 200
Aquifer 360

Permeate flow and salt rejection based:  32,000 ppm NaCl feed stream, 77°F, and pressure and recovery listed above.  Element Permeate flow may vary +/- 20%

Operating Limits for M-S2521A

Maximum Operating Temperature: 113°F (45°C)
Maximum Operating Pressure: 1,000 psig (69 bar)
Maximum Pressure Drop: 15 psig (1 bar)
Maximum Feed Flow Rate: 6 gpm (1.4m³/h)
pH Range, Continuous Operation: 2-11
pH Range, Short-Term Cleaning: 1-13
Maximum Feed Silt Density Index: SDI 5
Fere Clorine Tolerance: 0


Related Products for use with M-S2521A Seawater Elements

PRO-2.5-1200-EP-21 2.5x21 Fiberglass Membrane Housing for Seawater RO Membranes (Water Maker Pressure Vessel)
C-C2510-A11 Membrane Cleaning Cartridge with Acid Cleaner to Remove Scale Buildup and Prolong Membrane Life
C-C2510-A22 Membrane Cleaning Cartridge with Alkaline Cleaner to Remove Organics and Prolong Membrane Life
C-C2510-A88  Membrane Preservative Cartridge for Preserving the System and Membrane During Extended Periods of Non-Operation.
655139-03 Oil Absorbing Filter Cartridge - Oil-Water Separator Replacement Cartridge, 20" Big Blue Pentair Pentek  Filter
H-F10100CF Plankton Filter  - 10" Standard 100 Micron Spun Polypropylene Replacement Filter Cartridge

Common Applications for AMI Seawater Membrane Elements:

  • Seawater Desalination
  • Marine Applications
  • Watermaker RO Systems
  • Yachts

Physical Dimensions of AMI M-S2521A SWRO

Reverse Osmosis Membrane for Seawater Desalination Watermakers  
L 21.0 (533)
I 19.0  (480)
D 2.4 (6.1)
P 0.75 (1.9)


Replacement Compatibility for AMI 25x21 SWRO Membranes

AMI 2.5" x 21" membrane elements can be used as direct replacements for  DOW FilmTec DuPont SW30-2521, Katadyn Spectra FT-MB-20, and most industry-standard 2.5" x 21" seawater RO membranes, in SWRO systems using these elements. Some common systems using these elements are:

  • Spectra Ventura 150 
  • Spectra Ventura 150C
  • Spectra Ventura 200T
  • Spectra Ventura 200c
  • Spectra Catalina 340c Compact
  • Spectra Cape Horn Extreme 330 Compact
  • Spectra Newport 400c Compact
  • Spectra Aquifer 150
  • Spectra Aquifer 200
  • Spectra Aquifer 200 Expedition
  • Spectra Aquifer 200 Power Pack Solar
  • Spectra Aquifer 360
  • Katadyn Ventura 150 
  • Katadyn Ventura 150C
  • Katadyn Ventura 200T
  • Katadyn Ventura 200c
  • Katadyn Catalina 340c Compact
  • Katadyn Cape Horn Extreme 330 Compact
  • Katadyn Newport 400c Compact
  • Katadyn Aquifer 150
  • Katadyn Aquifer 200
  • Katadyn Aquifer 200 Expedition
  • Katadyn Aquifer 200 Power Pack Solar
  • Katadyn Aquifer 360
  • VT-150-12, VT-150-24
  • VT-150c-12, VT-150c-24
  • VT-200-T-12, VT-200-T-24, Ventura 200T Deluxe
  • VT-200-12, VT-200-24, VT-200c-12, VT-200c-24
  • CH-330S-12, CH-330S-24
  • NP-400cS-12, NP-400cS-24
  • AF-150-DC-12, AF-150-DC-24
  • AF-200-DC-12, AF-200-DC-24, AF-150-EX-24, AF-200-PPS
  • Flight Ready Aquifer 360, AF-360-DC-12, AF-360-DC-24

If you do not see your system listed or wish to learn more about compatibility, please contact us.  Our certified water treatment experts will be happy to discuss your application.  To ensure prompt and accurate information, please include as much information about your system as possible, such as:  model, manufacturer, model of membranes being replaced, any available. product manuals or literature associated with your system, and photographs of your system or membranes.