Illustration.
How a magnesium pool works
A mineral pool is a chlorinated pool. Instead of plain pool salt (sodium chloride), you add a mineral blend, and the chlorinator makes chlorine from it the same way a salt chlorinator does. Zodiac, for example, describes its MagnaPool minerals as about 30% magnesium chloride and 70% potassium chloride, with no added sodium, used with its own chlorinator and glass filter media. Because magnesium chloride does not add the same salinity as salt, Zodiac's rule of thumb is that seven bags of its minerals equal five bags of salt.
Compared
| Liquid chlorine | Salt chlorinator | Magnesium (mineral) system | |
|---|---|---|---|
| How chlorine gets in | You pour it in | Made from salt by the cell | Made from the mineral blend by the cell |
| Equipment | None extra | Salt chlorinator | A chlorinator suited to minerals; some systems specify their own filter media |
| Ongoing purchase | Liquid chlorine, often weekly | Pool salt, topped up | Mineral blend, topped up (more kilograms than salt for the same salinity) |
| Upkeep | Frequent dosing | Clean the cell, check salt | Clean the cell, check mineral level |
All three still need the same pH, chlorine and stabiliser checks.
The health claims
Mineral pools are often marketed with claims about skin, relaxation and muscle recovery. We do not repeat them: we have not found good evidence that soaking in a pool at these mineral levels does any of these things, and nothing here is health advice. What can be said plainly is that the water feels different to some people, and that a mineral pool is still a chlorinated pool.
If you switch an existing salt pool to minerals, check that your chlorinator is rated for them first. Ask the maker or your pool technician.
Common questions
What is a magnesium pool good for?
It is a way of running a chlorinated pool with less or no sodium salt. Health benefits claimed in marketing are not something we can confirm.
What are the disadvantages of a magnesium pool?
The minerals cost more per bag than salt and you need more kilograms for the same salinity; some systems need specific equipment.
Do you put salt in a magnesium pool?
Some systems use only the mineral blend; others mix minerals and salt. Follow your chlorinator maker's instructions.
Do you need to shower after a magnesium pool?
As with any chlorinated pool, rinsing off afterwards is a sensible habit.