Balancing Calcium In Spa Water

Of all the chemicals you need to keep track of in your spa pool, calcium probably seems rather innocuous. Calcium is present in all fresh water sources, so it’s unsurprising to find it in our spa water. However, that doesn’t mean we can ignore it. Calcium has the ability to wreak havoc on your spa in more ways than one. Too much calcium in your water can lead to scaly buildup on your water and around the spa’s componentry. It can also disrupt your pH and alkalinity levels, throwing your entire water chemistry out of wack in one fell swoop. On the other hand, spa pool water with too little calcium present can corrode components like your heater, jets, and even the shell. Considering all of that, we want to give you a comprehensive guide on how to keep your calcium levels balanced and your components healthy.

Total Hardness

It’s important to note that a lot of test strips will not provide a reading on your ‘calcium levels’, as such. They will give you a reading on your spa pool water’s ‘Total Hardness’. This refers to the amount of both calcium and magnesium dissolved in your water. If you see the terminology, ‘hard water’, it refers to a large amount of these two elements in your water, and the opposite for ‘soft water’. You’ll often find harder water in rural areas or smaller towns, and softer water in the bigger cities.

You don’t need to worry about the advanced mathematics required to work out your exact magnesium and calcium levels respectively, your total hardness is all you need to know. When you test your spa pool water with test strips, you want to see a reading in the range of 250-500ppm. For help on testing, see our ‘How to use Test Strips’ post.

How to Increase Your Water’s Hardness

If your water’s calcium level is too low, you want to reach for a product called Iluka Hardup. Add this product at a rate of 100g per 1000 litres of spa pool water to raise the hardness by approximately 100ppm. For ease of use, one capful of this product is 70g, meaning two capfuls will achieve the result explained above. See the dosing chart for your spa pool model on page 24 of our Spa Pool Water Care Handbook.

Tip: Calcium can take a while to dissolve, so it’s best to add to a bucket of spa water first, mix it by hand until it dissolves, then pour it into the spa.

How to Lower Your Water’s Hardness

Having a super-high ‘Total Hardness’ reading is quite an uncommon occurrence unless you’re living in a rural area on well or tank water. In some cases, it is caused by spa users treating their water with too much Iluka Hardup. This product does exactly what it promises, and if people aren’t making sure this has dissolved into the water properly and re-test too early, they can end up inadvertently adding extra doses out of impatience.

For those with naturally high Total Hardness in their water supply, you would ideally use a hose filter when you’re refilling your spa, to filter out as much calcium and other minerals as possible, then go on to add Iluka Hardup as required.

If you’ve perhaps added a little too much Iluka Hardup and Total Hardness is testing slightly high, you could drain a smaller amount of water out of the spa and just refill that amount to dilute your calcium level with fresh water.

If your calcium levels are completely off the charts, you should complete a full drain, and physically clean the spa before you refill it.

It’s important to remember, a calcium reading that’s too low or too high is not hard to fix. Make sure you stay consistent with your water testing and balancing and you won’t have calcium-related qualms ruining your soak.