Magnesium (Mineral) Pool Maintenance

November 8, 2023

When it comes to pools, magnesium (aka mineral) types are typically easier to maintain than their chlorine and saltwater counterparts. This is because the chemical reactions that happen take care of a lot of the work for you. But, that doesn’t mean they’re completely maintenance-free.

This guide goes over the basics involved in magnesium pool maintenance, plus how to keep it sanitary and look inviting all year long.

How magnesium sanitizes your pool water

Magnesium sanitizes the water in your pool through a magnesium chloride water purification system. This system is based on two chemical reactions.

The first reaction happens when the salts are exposed to electrolysis (which is when electricity separates the chemical compound’s elements). This produces chlorine ions. The second reaction occurs when the magnesium produced is exposed to hydrolysis. This produces magnesium hydroxide.

From there, the two byproducts combine with your pool’s filtration system to purify and clean the water. Chlorine ions get released into the water, disinfect it and kill algae, fungi and bacteria. The magnesium hydroxide acts as something called a  flocculant during this process. This means it causes dirt particles suspended in the water to come together, creating larger groups that the filtration system can more easily capture.

Pool maintenance basics still apply

Most of our Beginner’s Guide to Simple Pool Maintenance applies to magnesium pool maintenance, too. For example, you’ll still want to keep up with each of these basic factors, no matter what system you’re using:


Stagnant water makes an ideal breeding ground for viruses and bacteria. This is part of the reason it’s so important to run your pool pump regularly and let the water circulate.

Basic cleaning

This is the manual side of pool maintenance and involves skimming the surface, brushing the walls and step ladders and vacuuming the bottom. By removing contaminants from the water, you’re creating less opportunity for bacteria and viruses to thrive.

Pool filter maintenance

If you don’t look after your pump and filtration system, it’ll continuously perform worse over time. This also means a lot more manual work for you.

For more information about what a good mineral pool maintenance routine looks like, check out our pool maintenance guide.

Pool maintenance steps for magnesium pools

Now that you’ve got the basics down, let’s take a closer look at the maintenance specifics for a magnesium or mineral pool.

Test your pool water for metals

Before using a pool mineral sanitizer, you need to know what kind of metals your water source contains, and how much. The strips or kits that test for metals usually measure safe levels for drinking water.

To get the levels you need, take a sample of pool water to your local pool store for testing. If the metal – especially copper – levels are high, add a metal sequestrant to the water after you fill the pool.

Keep your pH balance in check

Maintaining an ideal pH balance is arguably the most essential part of pool maintenance for all kinds of swimming pools, including mineral or magnesium.

Ideally, the pH should stay between 7.4 and 7.6. If you start to get outside of this range, the water becomes more inviting for bacteria and far less welcoming to our skin and eyes.

Monitor the total alkalinity

Managing your pool’s alkalinity is crucial. Ideally, this should be within 100 ppm to 150 ppm (parts per million).

Calcium hardness

Finally, you’ll want to test regularly for calcium hardness, particularly if your pool is concrete. If that’s the case for you, aim for 200 ppm to 275 ppm. For a fiberglass or vinyl pool, 175 ppm to 225 ppm is ideal.

Add the minerals to your pool

Now that you’ve got these levels under control, go ahead and add the minerals to your pool. There are several different delivery methods you can use:

In-skimmer pool mineral systems

These are small baskets designed to sit in your pool skimmer. Simply place the minerals inside. The skimmer will draw water through them, adding the minerals to your pool.

Floating dispensers

These dispensers float around freely in your pool, submerging the mineral and chlorine cartridges. Once one of the cartridges is empty, the dispensers usually turn on their side, letting you know it’s time for a replacement.

Inline systems

Inline systems are integrated into your pool’s existing plumbing system. They’re typically a small unit that gets plumbed into an existing pipe, allowing the water to pass through the cartridge. Once installed, keep an eye on the cartridge and replace it when it’s depleted. No need for measuring and complicated math.

Add your supplemental chlorine or bromine

Whether you’re using chlorine or bromine, measure and add just a little at a time, testing in between until it reaches the correct level. For chlorine, this is 0.5 ppm, and bromine should be 1 ppm.

How to shock a magnesium pool

As with any pool, good magnesium pool maintenance calls for “shocking” your pool water once a week to kill bacteria and clear up the water. Do this a bit more regularly if your pool is used often or collects a lot of debris.

The pool shocking process involves adding some “pool shock” product to your water. The amount of pool shock you need to use isn’t the same across the board, since it varies drastically depending on the product, the state of your pool water and the volume of water being treated. But, don’t worry – the product’s instructions will give you all the information you need.

If it’s the first time you’re shocking your magnesium or mineral pool, use a regular chlorine shock product. Watch your measurements, as using too much chlorine-based pool shock can oxidize the copper and turn your water green.

After the first time, non-chlorine shock products are generally a better choice. Keep your chlorine levels low (0.5 ppm to 1 ppm) to allow the minerals to do their job. While you can use chlorine shock and wait for the levels to normalize, using non-chlorine alternatives lets you skip this step entirely and save time.

Finally, whenever you shock your pool, check its chemical balance after 24-48 hours to ensure it’s safe for swimming.