Key takeaway: A magnesium pool, also called a mineral pool, sanitises water with dissolved magnesium chloride at around 3,500 to 4,500 ppm, backed by roughly half the chlorine of a standard chlorine pool. Converting an existing pool typically costs $120 to $480 in minerals to establish, with top ups only a few times a year after that.
If you’ve heard a mineral pool feels “softer” than a normal one and wondered what’s actually in the water, here’s the short version. A magnesium pool runs on magnesium chloride, and usually potassium chloride too, dissolved into the water at a set concentration, with a chlorinator cell converting a small amount of it into chlorine as it circulates. It’s not a chlorine-free pool, whatever the brochure implies, but it does run on noticeably less chlorine than a standard pool. Here’s how it stacks up against chlorine and salt pools, and what it actually costs to run one in Australia.
Magnesium vs Salt vs Chlorine Pools at a Glance
| Feature | Chlorine Pool | Salt Pool | Magnesium (Mineral) Pool |
| Sanitiser source | Added chlorine (granules, liquid or tablets) | Salt, via a chlorinator cell | Magnesium chloride, via a chlorinator cell |
| Typical chlorine level | 1 to 3 ppm | 1 to 3 ppm (cell-generated) | Around 0.5 ppm |
| Feel on skin and hair | Can dry skin and hair, stronger chlorine smell | Softer than chlorine, mild residue | Softest feel of the three, often marketed for sensitive skin |
| Corrosion risk to fittings | Low | Higher, salt is corrosive to ladders, heaters and metal fixings over time | Lower than salt, though your equipment still needs to be rated for it |
| Typical setup cost | Baseline (no cell required) | Moderate premium for the cell and initial salt | Similar to or slightly above a premium salt system, depending on supplier |
| Ongoing chemical cost | Highest, buying chlorine through the season | Low once the salt level is established | Around $120 to $480 to establish, then only a few top-ups a year |
What a Magnesium Pool Actually Does to the Water
A magnesium pool dissolves mineral salts, mostly magnesium chloride, at a concentration your system’s chlorinator is calibrated for, commonly somewhere in the 3,500 to 4,500 ppm range. The cell uses electrolysis to strip off a small, steady stream of chlorine, around 0.5 ppm, as water passes through it, enough to sanitise the pool without the sharper smell or eye sting people associate with a heavily dosed chlorine pool. The magnesium also binds to fine debris and helps it clump together, so it filters out more easily, which is one reason mineral pool owners often report clearer water with less clarifier. If you want the fuller picture on how sanitiser levels and water balance work together, our guide to pool water chemistry covers the basics that apply across chlorine, salt and magnesium systems alike.
Converting to Magnesium: A Worked Cost Example
Mineral salts are sold in bags, typically 25kg for around $30 to $60 depending on brand and retailer. A typical suburban family pool needs 4 to 8 bags to establish the right concentration when you first convert, so budget $120 to $480 for that initial dose. After that, most owners aren’t topping up monthly. Expect a few top-ups a year, alongside monthly salinity testing to keep the system in range. That’s a meaningfully different cost pattern to a standard chlorine pool, where you’re buying chlorine through the whole season instead, so it’s worth weighing this against your own salt dosing costs if you’re converting from salt rather than starting from a plain chlorine pool. Costs vary by brand and by the mineral concentration your specific chlorinator is designed for, so check your system’s manual or supplier before buying in bulk.
Pros and Cons of a Magnesium Pool
Pros
- Noticeably softer on skin, hair and eyes than a standard chlorine pool, and often recommended for eczema-prone skin
- Roughly half the chlorine of a standard pool, with less of the sharp “pool smell”
- Magnesium helps clump fine debris for easier filtering, which can mean less clarifier use
- Some systems are designed to cut backwash water use significantly compared with a standard sand filter setup
Cons
- Still relies on chlorine, just less of it. It isn’t a chlorine-free pool no matter how it’s marketed, and it still needs roughly the same care as a standard chlorine dosing routine, just at a lower level
- Can be prone to scale and staining if the water balance isn’t kept in range
- Ongoing testing (monthly salinity checks) is still real maintenance, not “set and forget”
- Setup cost estimates vary a lot supplier to supplier. Get a written quote before assuming it will be cheaper or pricier than a premium salt system
If a supplier tells you a magnesium pool is maintenance-free, that’s a sales line, not a fact. You’ll still test the water and top up minerals through the year, just less often than you’d buy chlorine for a standard pool.
Frequently Asked Questions
What is a magnesium pool?
A magnesium pool, also called a mineral pool, is a swimming pool sanitised with dissolved magnesium chloride minerals instead of plain salt, with a chlorinator cell converting a small amount of that magnesium chloride into chlorine as the water circulates.
What does a magnesium pool do to the water?
It changes the water’s mineral content and feel rather than removing chlorine altogether. Magnesium at roughly 3,500 to 4,500 ppm gives the water a softer, silkier feel, reduces the sharp chlorine smell, and helps fine debris clump together for easier filtering.
Do magnesium pools still need chlorine?
Yes. A magnesium pool typically runs at around 0.5 ppm chlorine, roughly half of what a standard chlorine pool needs, but it isn’t chlorine-free.
Is a magnesium pool cheaper to run than a salt pool?
Not necessarily. Converting to magnesium usually costs $120 to $480 in minerals up front with only a few top-ups a year, but salt pools already run on relatively low ongoing costs too, so the cheaper option depends on your existing setup, your pool’s size, and the prices your local supplier charges.
Can I convert an existing chlorine or salt pool to magnesium?
In most cases yes, provided your chlorinator cell and other equipment are compatible with magnesium chloride at the concentration your system needs. Check with the equipment manufacturer or your pool technician before buying minerals, since not every cell is rated for it.
