The right reverse osmosis membrane depends on your system’s housing size, daily water capacity, and intended use. For standard under-sink systems, the Membrane Solutions 50 GPD membrane is a fit-focused option, while the iSpring 75 GPD membrane is suited to buyers seeking greater stated capacity. Applied Membranes and Metpure offer other 50 GPD replacement choices, and Aquatic Life’s cartridge pack includes a membrane for compatible aquarium RO/DI systems. Always check the membrane dimensions and system requirements before ordering.
| Product | Best For | Stated Capacity |
|---|---|---|
| Membrane Solutions RO Membrane | Standard-size residential housings | 50 GPD |
| iSpring Greatwell RO Membrane | Higher stated daily output | 75 GPD |
| Applied Membranes RO Membrane | Replacement buyers seeking stated NSF/ANSI 58 certification | 50 GPD |
| Metpure RO Membrane | Standard-size 50 GPD replacement | 50 GPD |
| Aquatic Life Cartridge Pack | Compatible aquarium RO/DI systems | 75 GPD membrane |
Membrane Solutions 50 GPD RO Membrane
This replacement membrane is designed for buyers who need a 50 GPD element sized for standard residential RO housings. Its listed dimensions are 11.75 by 1.75 inches, and the manufacturer describes it as compatible with standard 1812/2012 membrane housings with a 2-inch internal diameter.
The product features a thin-film composite membrane and lists a stabilized salt rejection rate of up to 97%. It is described as independently tested to meet NSF/ANSI 58 standards. These specifications make it a useful option when matching a conventional under-sink membrane by size and capacity.
Best for: Owners of compatible 50 GPD systems who have verified the housing dimensions. Caution: “Fits most” does not mean it fits every RO system; confirm the housing and system requirements before purchase.
iSpring Greatwell 75 GPD Membrane
The iSpring Greatwell membrane is a 75 GPD replacement intended for standard under-sink RO membrane housings. It measures 11.75 by 1.75 inches, which can help buyers compare it with the original element in their system. The product description states a TDS rejection rate of up to 97% under NSF/ANSI 58 testing conditions.
The manufacturer says the membrane is independently tested to meet NSF/ANSI standards and can reduce a range of listed contaminants, including lead, fluoride, arsenic, and sodium. Its stated capacity is higher than the 50 GPD options in this guide, making it better for buyers whose RO system calls for a 75 GPD membrane.
Best for: People replacing a compatible 75 GPD membrane who want to match the listed standard dimensions. Caution: Capacity and fit depend on the RO system; check its manual rather than assuming any standard-size membrane will work.
Applied Membranes 50 GPD RO Membrane
Applied Membranes lists this 50 GPD replacement as a universal-fit membrane for standard 1812/2012 housings with a 2-inch inner diameter. Its listed dimensions are 1.8 by 12 inches, so compare those measurements with your existing membrane and housing before selecting it.
The product description states that it removes up to 99% of total dissolved solids and is certified to NSF/ANSI 58 for material safety and reduction of specified contaminants. It is manufactured at the company’s facility in Vista, California, according to the product details.
Best for: Buyers seeking a 50 GPD membrane with stated NSF/ANSI 58 certification and standard-housing compatibility. Caution: The “universal” description is not a substitute for checking the exact housing size and the RO system maker’s guidance.
Metpure 50 GPD RO Membrane
Metpure’s replacement is listed as a 50 GPD membrane measuring 11.75 by 1.75 inches. The product description says it fits most standard under-sink membrane housings, including universal 2.5-by-12-inch RO membrane housings. Its stated construction is thin-film composite material.
The manufacturer claims up to 99% reduction of more than 1,000 impurities, with examples including lead, fluoride, arsenic, and sodium. For comparison, the product’s stated capacity matches the Membrane Solutions and Applied Membranes options, but its description emphasizes broad contaminant-reduction claims.
Best for: Buyers seeking a standard-size 50 GPD replacement and checking their housing dimensions against the listing. Caution: The supplied product details do not specify an independent certification, so do not assume certification from the performance claims alone.
Aquatic Life Twist-In Cartridge Pack
This pack includes a 75 GPD membrane along with sediment, carbon block, and deionization cartridges. It is intended for Aquatic Life Twist-In RO systems and is a different kind of purchase from a standalone replacement membrane: the buyer receives multiple stages together.
The listed sediment cartridge addresses materials such as sand, silt, and rust. The carbon block is described as reducing chlorine, while the membrane is stated to reduce TDS. The product description specifically notes that the carbon filter does not remove chloramines.
Best for: Owners of compatible Aquatic Life Twist-In aquarium RO/DI systems who need the included cartridges as well as the membrane. Caution: Avoid this option if you only need a standalone membrane or if your water-treatment needs include chloramine removal.
Buying Guide: How To Choose An RO Membrane
Which membrane size and capacity should I buy?
Start with the RO system’s manual or the label on the current membrane. Match the stated GPD capacity, membrane length and diameter, and housing type. The products here include 50 GPD and 75 GPD options; choosing a different capacity solely because it appears higher may not suit the system.
What do GPD and TDS rejection mean?
GPD means gallons per day, a stated production capacity for the membrane. Actual output can depend on operating conditions and the RO system. TDS rejection describes reduction of total dissolved solids. A rejection claim is not a guarantee that every contaminant is reduced equally, so review the product’s specific claims and your water-treatment needs.
Should I replace only the membrane?
A standalone membrane makes sense when the other filters are in serviceable condition and the system calls for that replacement. A cartridge pack may be more appropriate when multiple stages need replacement, but confirm that every cartridge matches your system. Follow the manufacturer’s maintenance schedule and installation instructions.
Do aquarium RO/DI membranes work for drinking-water systems?
Do not assume they are interchangeable. The Aquatic Life pack is described for compatible Twist-In aquarium RO/DI systems. Drinking-water systems and aquarium systems can have different cartridge arrangements and intended uses. Select a product specified for your system.
Frequently Asked Questions
How do I know if an RO membrane will fit?
Check the RO system model, membrane housing, membrane dimensions, and required capacity. Compare these details with the replacement listing before ordering.
Is a 75 GPD membrane always better than a 50 GPD membrane?
No. The correct capacity is the one specified for your system. A higher stated GPD does not establish compatibility with a system designed for another membrane.
Does an RO membrane remove chlorine?
These products list different filtration stages and claims. In the Aquatic Life pack, chlorine reduction is attributed to the carbon block, not specifically to the membrane. Check the complete system’s filtration stages.
Can I use a membrane labeled “universal” in any RO system?
No. “Universal” describes broad compatibility, not guaranteed fit. Verify the housing dimensions, capacity, and manufacturer recommendations for your specific system.