Alkaline Filters for Reverse Osmosis. From basic pH to full remineralization.
Alkaline water filters install inline after a reverse osmosis system to raise pH, restore minerals, and improve taste. GoodFor is a Carlsbad, California water filtration brand. We carry two inline cartridges: a standard alkaline filter ($36) for basic pH adjustment, and the Sango Coral ($289) — a comprehensive upgrade restoring 70+ trace minerals from fossilized Okinawan coral. Both work with any RO system.
Two alkaline filters. One simple choice.
Both install inline after any reverse osmosis system. The Alkaline Filter is the standard pH-adjustment option. The Sango Coral is the upgrade — comprehensive remineralization with 70+ trace minerals.
Alkaline Filter
A standard inline alkaline cartridge that raises the pH of reverse osmosis water from its naturally acidic post-RO state (6.0–7.0) into the mildly alkaline range. Adds basic alkalizing minerals. Installs in minutes with standard inline connections, no maintenance, works with any RO system. The widely-used starting point for anyone adding alkaline water at the kitchen tap.
GoodFor Sango Coral
340g of fossilized Okinawan Sango coral. Restores 70+ trace minerals in ionic, bioavailable form — calcium and magnesium at the natural 2:1 ratio, plus potassium, iron, silicon, chromium, sulfur, iodine, and 60+ more. The remineralization stage of GoodFor's Hydration Stack, sold standalone for anyone with an existing RO. Available in both ¼" and ⅜" John Guest push-fit — fits any under-sink RO line.
Which alkaline filter is right for you?
Both filters install inline after a reverse osmosis system. The Alkaline Filter ($36) is the standard entry-level option for raising pH and adding basic minerals. The Sango Coral ($289) is the comprehensive upgrade — 70+ trace minerals from fossilized Okinawan coral at the natural 2:1 calcium-to-magnesium ratio.
| Alkaline Filter | GoodFor Sango Coral | |
|---|---|---|
| Price | $36 (was $39) | $289 |
| Type | Basic alkaline cartridge | Comprehensive remineralization |
| What it does | Raises pH; adds basic alkalizing minerals | Restores 70+ trace minerals + raises pH naturally |
| Mineral profile | Basic alkaline media | Calcium & magnesium (2:1 ratio), potassium, iron, silicon, chromium, sulfur, iodine + 62 more |
| Source media | Standard alkaline ceramic | Fossilized Okinawan Sango coral (340g) |
| Particle size | Standard | 8μm ultra-fine (cellular absorption) |
| pH effect | Raises pH to mildly alkaline range | Raises pH naturally via added minerals |
| Cartridge life | Per manufacturer spec | ~24 months |
| Subscribe & Save | No | Yes |
| Compatible with any RO | Yes (standard inline) | Yes — ¼" and ⅜" John Guest push-fit |
| In the Hydration Stack | No | Yes (the remineralization stage) |
| Best for | Budget pH adjustment | Comprehensive water optimization |
By buyer profile — which filter to choose.
What is an alkaline filter for reverse osmosis water?
An alkaline filter for reverse osmosis water is an inline cartridge installed after the RO membrane that raises the pH of purified water and adds minerals back. Reverse osmosis removes nearly all dissolved minerals along with contaminants, leaving water slightly acidic (pH 6.0–7.0) and mineral-empty. An alkaline filter restores both — raising pH into the mildly alkaline range (typically 7.5–8.5) and reintroducing calcium, magnesium, and other minerals depending on the cartridge type.
Alkaline filters for RO come in two main types:
Standard alkaline filters use simple alkalizing media — ceramic balls, calcite, or basic mineral compounds — to raise pH and add a small amount of basic minerals. They're the widely-used entry point: low cost, low maintenance, easy to install. GoodFor's Alkaline Filter ($36) is a standard alkaline cartridge in this category.
Remineralization filters go further. They use mineral media that releases a comprehensive profile of trace elements into the water — typically calcium, magnesium, potassium, and dozens of additional trace minerals in bioavailable, ionic form. GoodFor's Sango Coral ($289) is a remineralization filter: 340 grams of fossilized Okinawan Sango coral that releases 70+ trace minerals at the natural 2:1 calcium-to-magnesium ratio. It's the same cartridge that makes up the remineralization stage of the Hydration Stack, GoodFor's most popular drinking water system.
Both install inline after any reverse osmosis system, GoodFor's or another brand's. Both ship nationwide. The choice depends on what you want back in your water — pH adjustment alone, or the full mineral profile your body recognizes for daily function.
What RO removes — and why your body needs it back.
RO water tests near-zero on a TDS meter. That number isn't only contaminants — it's also the minerals.
Taste is the most common reason people buy.
People who switch from RO-only water to remineralized RO water consistently describe the taste change as the single most noticeable benefit. RO water is sometimes described as "flat" or "thin" — the absence of mineral content registers on the palate. Restoring minerals restores the dimension. Most alkaline shopping is, at its core, taste shopping.
Calcium and magnesium are the two minerals RO strips most.
Reverse osmosis membranes have a pore size of approximately 0.0001 micron. They reject dissolved solids by molecular size — including calcium and magnesium. The result is water that tests near-zero on a TDS meter. The World Health Organization's 2009 report on calcium and magnesium in drinking water formally noted the public health significance of these minerals.
pH is the side effect of mineralization — not the goal.
Pure water sits near pH 7.0. RO water tests slightly acidic at 6.0–6.5 because trace dissolved gases form weak carbonic acid in the absence of buffering minerals. Adding alkaline minerals — calcium, magnesium, potassium — naturally raises pH into the 7.5–8.5 range. Sango Coral does this by adding minerals; the Alkaline Filter does it with alkalizing media.
Why fossilized Okinawan coral?
Okinawa is one of the world's five Blue Zones — regions documented for an unusually high proportion of residents living past 100. The Okinawa Centenarian Study, led by Dr. Makoto Suzuki and one of the most-cited longevity studies in modern research, has examined the diet, water, and lifestyle of the long-lived Okinawan population since 1976.
One detail from that research is consistently surfaced: traditional Okinawan drinking water was filtered through fossilized Sango coral reefs. The water picked up ionic, bioavailable mineral content as it passed through the coral — calcium, magnesium, and dozens of trace elements — at the same 2:1 calcium-to-magnesium ratio found in healthy intracellular fluid and bone.
The GoodFor Sango Coral cartridge replicates that filtration step in a modern under-sink format. The coral is sustainably harvested from fossilized seabeds — never from living reefs. It's processed to an ultra-fine 8μm particle size that supports cellular absorption.
The result: 70+ trace minerals delivered the way the body has used them for as long as humans have been drinking water — in ionic form, in natural ratios, at a dose your body recognizes for daily homeostasis.
Where mineral filters fit in an RO system.
Installation order matters. The mineral cartridge installs after the RO membrane — before the faucet.
Cold Water Line
Source water from your home supply
RO System
MM8500, MM7000, or any other brand
Mineral Filter
Sango Coral or Alkaline installs here
UMH Pure
Optional structuring device — always last
Faucet
Drinking water at the tap
Both filters use standard inline connections and install in minutes. The Sango Coral is available in both ¼" and ⅜" John Guest push-fit — the two universal under-sink RO line sizes — so it fits any system. No tools required. No electricity, no drain line, no monitoring. New to the under-sink stack? Our drinking water optimization page walks through how filtration, remineralization, and structuring fit together.
Add minerals back in minutes.
Both filters ship nationwide. Both install in minutes without tools. The Sango Coral is the recommended starting point for any RO owner ready to upgrade their drinking water beyond purification.
Not sure where to start? Talk to our team — every consultation is free.
Alkaline filters for RO water, answered.
What is an alkaline water filter?
An alkaline water filter is a cartridge that raises the pH of drinking water above neutral (7.0) into the mildly alkaline range, typically 7.5–9.5, by adding alkalizing minerals. Most alkaline filters used with reverse osmosis systems install inline after the RO membrane and use media such as calcite, ceramic balls, or mineral compounds to release calcium, magnesium, and other minerals into the water as it passes through. The pH increase happens as a side effect of those minerals dissolving into the water.
Which alkaline filter is best for reverse osmosis water?
The best alkaline filter for reverse osmosis water depends on what you want back in your water. For basic pH adjustment on a budget, a standard alkaline cartridge like the GoodFor Alkaline Filter ($36) is the widely-used entry point — it raises pH and adds basic alkalizing minerals. For comprehensive remineralization with a full trace mineral profile, the GoodFor Sango Coral ($289) uses 340 grams of fossilized Okinawan coral to release 70+ trace minerals in ionic form at the natural 2:1 calcium-to-magnesium ratio. Both install inline after any RO system.
Do alkaline filters add minerals or just raise pH?
Alkaline filters do both, but the extent varies significantly by cartridge type. Standard alkaline filters add a small amount of basic alkalizing minerals — typically calcium and magnesium in low concentrations — which is what causes the pH rise. Remineralization filters like the Sango Coral add a comprehensive mineral profile: calcium and magnesium at higher concentrations (10–30 mg/L and 5–15 mg/L respectively), plus potassium, iron, silicon, chromium, sulfur, iodine, and dozens of trace elements. The pH increase in both cases is the side effect of mineral addition, not the primary function.
How do you remineralize reverse osmosis water?
The most effective way is with an inline remineralization cartridge installed after the RO membrane. The cartridge contains mineral media — most commonly calcite, ceramic balls, or coral — that releases calcium, magnesium, and trace minerals into the water as it passes through on the way to the faucet. Inline cartridges are the lowest-maintenance method: install once, replace every 1–2 years depending on the cartridge, and never measure or add anything daily. Alternatives include mineral drops, alkaline pitchers, and mineral salts, but none offer the consistency of an inline cartridge.
What's the difference between an alkaline filter and a remineralization filter?
An alkaline filter is a pH-adjustment device — it uses alkalizing media to raise the pH of water into a mildly alkaline range, typically without adding a comprehensive mineral profile. A remineralization filter is broader — it adds back specific minerals (calcium, magnesium, potassium, and dozens of trace minerals) that have nutritional and physiological value. The pH increase in a remineralization filter is the side effect of adding those minerals. GoodFor's Sango Coral is a remineralization filter; the standalone Alkaline Filter is a pH-adjustment cartridge.
Is reverse osmosis water unhealthy without remineralization?
Drinking RO water in normal quantities is not harmful for healthy adults. However, the World Health Organization's 2009 report on calcium and magnesium in drinking water has published guidance noting the public health significance of these minerals for cardiovascular and metabolic function, and many practitioners support remineralizing RO water — particularly for households where it is the primary source of drinking and cooking water. According to the NIH Office of Dietary Supplements, most adults in the United States do not meet recommended magnesium intake from diet alone, so water that contributes to mineral intake rather than being mineral-empty has practical value.
What is Sango coral and where does it come from?
Sango coral is a type of fossilized coral native to the seabeds around Okinawa, Japan. It is sometimes referred to as "Okinawa Gold" for its mineral content. The coral is harvested sustainably from fossilized deposits on the ocean floor — never from living reefs. Once collected, it is processed into fine granules and packed into water filter cartridges. The minerals release into water in ionic, bioavailable form at the natural 2:1 calcium-to-magnesium ratio found in healthy intracellular fluid. The Okinawan population has historically consumed water filtered naturally through fossilized Sango coral reefs, a fact noted in the long-running Okinawa Centenarian Study on regional longevity.
How much calcium and magnesium does a remineralization filter add?
A remineralization cartridge typically raises calcium content by 10–30 mg/L and magnesium by 5–15 mg/L, depending on the cartridge media, flow rate, and water chemistry entering the cartridge. The GoodFor Sango Coral uses 340 grams of food-grade Okinawan Sango coral processed to an 8μm particle size, releasing minerals in ionic form at the natural 2:1 calcium-to-magnesium ratio. The exact output varies with usage. Cartridge output declines gradually over the 24-month service life, which is the recommended replacement interval.
How long does a remineralization filter cartridge last?
The GoodFor Sango Coral cartridge has a recommended replacement interval of approximately 24 months. Cartridge life depends on household water usage — homes with higher daily consumption will see mineral output decline sooner. The Alkaline Filter has a shorter cycle and should be replaced per the included manufacturer spec. Subscribe & Save is available on Sango Coral replacement cartridges.
Can I add a remineralization filter to my existing RO system from any brand?
Yes. Both the Sango Coral and the Alkaline Filter are designed to work with any reverse osmosis system — not just GoodFor's MicroMax 7000 or 8500. The Sango Coral is available in both ¼" and ⅜" John Guest quick-connect push-fit sizes — the two universal under-sink RO line standards — so it pairs with virtually any setup. If you already own an RO from another brand and want to add remineralization, the Sango Coral is the upgrade path most customers choose.
Will a remineralization filter make my water taste better?
Almost always, yes. RO water on its own is often described as flat, thin, or oddly tasteless — the absence of mineral content registers on the palate as a missing dimension. Adding back calcium, magnesium, and trace minerals restores that dimension. This is the most common reason customers describe their post-Sango Coral water as the moment they stopped reaching for bottled water.
Is alkaline water actually better for you?
Research on alkaline water for general consumption is mixed. There is no strong evidence that drinking water with a pH of 8.5 versus 7.0 produces meaningful health benefits in healthy adults. What is well-supported is the role of dietary minerals — particularly calcium and magnesium — in cardiovascular and metabolic health. The case for a mineral filter is stronger than the case for pH alone. Sango Coral delivers both: a comprehensive mineral profile plus the natural pH lift that comes from those minerals.
Does an alkaline or mineral filter remove contaminants?
No. Mineral filters add minerals back to water — they do not remove contaminants. The contaminant removal work is done by the RO system itself. The MicroMax 8500, for example, is certified to NSF/ANSI 42, 53, 58, 401, and 372 for the removal of chlorine, lead, PFAS, fluoride, arsenic, pharmaceuticals, and dissolved solids. The mineral filter is the second step that runs after that removal is complete. If you don't yet have a reverse osmosis system, the drinking water optimization page covers the full sequence.