Carol Tweed
Published:
August 14, 2026
Last Updated:
If you have been researching swimming pool options lately, you have likely run into the massive marketing push for magnesium “mineral” pools. The advertisements promise a luxurious, therapeutic oasis that heals your skin and detoxes your body.
But what does the actual science say? Are magnesium pools worth the extra cost?
When you strip away the high-end marketing, the truth is simple: regular pool salt (NaCl) is vastly cheaper, just as effective at sanitising, and you can mimic that premium “soft water” feel for a fraction of the cost using borates (Optimise is the commercial name of the product – available in our stores).
The Science: Salt is Salt
Here is the chemical reality that pool companies rarely highlight: both standard saltwater chlorinators and magnesium systems create the exact same sanitiser.
Whether you add low-cost sodium chloride (NaCl) or expensive magnesium chloride (MgCl₂) to your pool, the chlorinator ultimately produces the same sanitiser: hypochlorous acid (HOCl). The cell first generates chlorine gas from the chloride ions, and this chlorine immediately reacts with water to form hypochlorous acid, which kills bacteria and algae.
From a pure sanitation standpoint, magnesium offers zero extra killing power. Your water is not “cleaner” or “safer” just because the chlorine came from magnesium.
The Health Myth vs. Reality
Marketing teams love to claim that swimming in a magnesium pool boosts your body’s magnesium levels or “detoxes” your system. However, peer-reviewed medical studies on transdermal absorption show that the human skin is an incredibly effective barrier. Immersing yourself in a magnesium pool does not raise the body’s magnesium levels in any measurable way compared to a healthy diet or supplements (there’s a lot of myths about dietary supplementation too).
“Detox” is also misleading. Your liver, kidneys and digestive system remove waste; sweating contributes very little. Magnesium may be prescribed for specific medical purposes or to correct a deficiency, but that is not the same as detoxification.
The Hidden Headache: Testing and Monitoring
Beyond the high cost, magnesium pools introduce a major maintenance headache: they are incredibly difficult to test accurately. Standard test kits cannot separate magnesium from calcium—they just lump them together as “total hardness“. This makes it very easy to miscalculate your actual calcium levels, risking scale buildup on your chlorinator or damage to your pool surfaces.
In fact, even professional pool shops using automated, digital spin-disk scanners struggle with magnesium. Because the machines have to use expensive, specialty testing disks to separate calcium from magnesium using complex mathematical subtraction algorithms, even commercial equipment can deliver erratic results. If professionals with high-end lab tools find it tough to get a consistent, trustworthy reading, everyday pool owners stand no chance.
How to Get the "Mineral Pool Feel" for Less
People love magnesium pools because the water feels silky and is gentle on the eyes. But you do not need to pay a premium or deal with chemistry headaches to get these same benefits.
You can achieve the exact same effect by adding borates to a standard, easy-to-manage saltwater pool.
Adding the correct levels of borates (usually around 30 to 50 ppm) to your pool water provides incredible benefits:
- Silky Water Feel: Borates lower the surface tension of the water, giving it that exact “smooth” texture associated with high-end mineral pools.
- pH Stability: Borates act as an excellent pH buffer, preventing the rapid pH spikes common in saltwater pools. This means you will use less acid over the season.
- Algae Prevention: Borates function as a mild algaecide, giving you an extra layer of protection against a green pool. Experience has also shown that you can reduce the level of chlorine in the pool water.
Salt vs. Magnesium in a Swimming Pool: The Sensory "Soft Feel"
When you add salt or magnesium directly into a pool, you are adding minerals to the water, not removing them. From a strict chemistry standpoint, adding minerals actually makes the water harder, but it feels completely different to our bodies due to biology and physics.
1. Standard Saltwater Pool (NaCl)
- The Feel: High-quality saltwater pools feel smooth because the salinity matches our body’s natural chemistry much closer than raw, fresh tap water.
- The Science: Our eyes, tears, and skin cells have a natural salinity level of roughly 3,500 to 9,000 ppm. Fresh tap water has almost zero salt, creating an osmotic imbalance that pulls moisture out of your skin and eyes, causing that tight, itchy feeling. When you add pool salt (usually around 3,000 to 4,000 ppm), the water is closer to your body’s natural balance, eliminating that osmotic sting and creating a naturally comfortable, smoother feel.
2. Magnesium Mineral Pool (MgCl₂)
- The Feel: Magnesium pools feel distinctly “silky” or even slightly slippery on the skin compared to standard saltwater.
- The Science: Magnesium chloride is a highly hygroscopic compound, meaning it binds strongly to water molecules and holds onto moisture. When you swim in a magnesium pool, a microscopic layer of hydrated magnesium ions remains temporarily bound to your skin and hair after you step out. This creates a physical barrier that prevents evaporation, leaving your skin feeling moisturised and silky rather than dried out.
Why Borates are the Ultimate Shortcut
This brings us back to why borates are such a powerful addition to a standard saltwater (NaCl) pool.
Borates significantly lower the surface tension of the pool water. By breaking down that surface tension, the water physically blankets your skin more uniformly, mimicking that ultra-luxurious, slippery, “silky” texture of a magnesium pool.
By using standard salt, you get the comfortable osmotic balance that prevents eye and skin irritation. By adding borates, you get the physical silkiness of a premium mineral pool—all without the high cost of magnesium bags or the testing nightmares at your pool shop
The Bottom Line
Do not let clever marketing convince you to spend double or triple on proprietary magnesium blends, specialised testing, and complex monitoring. Stick to affordable, reliable sodium chloride (NaCl) to sanitise your pool, and add borates to get that ultra-luxury, silky water feel.
Your pool will be crystal clear, your chemistry will be easy to manage, and your wallet will thank you. The best pool is one that is properly designed, sanitised and maintained.
Water balance, filtration, circulation and sanitation generally have a greater impact on swimmer comfort and water quality than marketing claims surrounding any particular mineral blend.
FAQ - Magnesium Pools
No, magnesium pools are not worth the extra cost. Magnesium and standard saltwater chlorinators produce the same sanitiser, hypochlorous acid (HOCl), so magnesium provides no additional sanitising power. A standard saltwater pool with borates can provide the comfortable, silky water feel associated with a magnesium pool without the higher cost and complicated water testing.
The main disadvantages of magnesium pools are higher costs and more difficult water testing. Standard pool tests measure magnesium and calcium together as total hardness, making it harder to determine the actual calcium level. Incorrect calcium readings can increase the risk of scale buildup on the chlorinator or damage to pool surfaces.
Yes, a magnesium pool is more expensive to run than a standard saltwater pool. Magnesium chloride and proprietary mineral blends cost more than standard sodium chloride pool salt. Magnesium pools can also require specialised testing and more complex monitoring, adding to the overall cost of pool maintenance.