Low Calcium Symptoms
- Etching of pool surface
- Pitting on pebble surface
- Tile grout eroding away
- Pool water cloudy
- Fibreglass turning white
High Calcium Symptoms
- Clogged filter / Reduced Circulation
- Pool surface feels rough
- White 'blotchy' areas on pool surface
- Cloudy water
- Skin feels dry and sticky after swimming
Calcium hardness - Facts & Myths
Maintaining proper calcium hardness in your pool water is crucial for preserving and protecting the pool surface and preventing issues like staining, etching, or discoloration. Unlike pH and chlorine levels, which can fluctuate seasonally, calcium hardness tends to remain relatively stable. Here’s a concise summary:
Balancing Calcium Hardness
Calcium hardness: Affects the water’s ability to dissolve minerals. It’s essential to strike the right balance. Not too high and not too low.
Testing Frequency: Test every few months, as significant variations are uncommon.
Effects of calcium hardness being off balance
High Calcium Hardness: Can lead to white staining and calcium formation on pool surfaces.
Low Calcium Hardness: May cause etching or discoloration on both pebble and fibreglass pools. Remember that fiberglass pools DO NEED some calcium to protect the gelcoat.
Maintenance: Adjust calcium levels as needed to keep them within the recommended range.
Remember, understanding these nuances and ensuring optimal water chemistry will protect your pool surface and equipment. If you have any more questions, feel free to ask!
What about calcium hardness reducers?
Some novice pool technicians think that a ‘calcium hardness reducer’ will permanently lower the calcium level. However, this is simply not the case. This is because the calcium isn’t actually ‘removed’ from the water with these treatments. Remember, these ‘reducers’ work by using chemicals to bind up (or capture) the calcium temporarily. These treatments do reduce the effects of high calcium in the short term. However, after 4-6 weeks, these products are completely broken down by normal water chemistry. Remember, when this happens, the calcium is simply released from the chemical bond and then returns to the water. Finally, after about 5 weeks your calcium level is back to where you started! Then, you need to buy more calcium hardness reducer and do it all over again.
Topping up the pool water will help, right?
Simply “topping up” your pool will not lower calcium hardness levels. While water evaporates, calcium remains behind, becoming more concentrated over time. Adding fresh water only replaces the volume lost to evaporation; it does not remove the existing mineral buildup.
Concrete pools naturally leach calcium into the water, a process that is most aggressive when the pool surface is new. To maintain a healthy chemical balance, it is essential to test your water levels regularly, particularly during the first few months of operation.
My calcium hardness is low? Isn’t that good?
How do I reduce my calcium hardness?
The only way to properly lower your calcium hardness level is to pump out (through back washing or draining) a small amount of existing pool water and then refilling. This lowers the level because you are taking calcium-rich water out of the pool and replacing it with tap water with very low calcium levels. Depending on where you live, most tap water in Australia has a calcium hardness of around 50ppm (Sydney water) while tank and rainwater contain no calcium at all. So, following this “drain and refill process” will lower the calcium level without chemicals! So, if you live in a region that has ‘hard’ water or mineral-rich water, then have the calcium level of your tap water measured before starting this process. Remember, you don’t have to drain the entire pool to lower the calcium level. In many cases, replacing as little as 30-40 cm’s of water will bring your pool back into the normal calcium range.
Calcium reduction…the natural way.
One way to reduce calcium hardness is to pump out water using your pool cleaner or vacuum hose. Doing this during long periods of soaking rain when your pool is likely to overflow is best. In short, this method removes the high calcium water from the pool while at the same time, the rain refills it with fresh water that contains no calcium. So, doing this several times a year can have a huge impact on the calcium levels in your water. And it’s free!
Hardest water cities in Australia
| Rank | City & State | Typical Calcium Hardness (ppm) | Primary Water Source |
|---|---|---|---|
| 1 | Regional WA, WA | 200+ ppm | Groundwater Bores |
| 2 | Alice Springs, NT | 190-210+ ppm | Amadeus Basin Aquafiers |
| 3 | Inland NSW, NSW | 180+ppm | Bore Water / Rivers |
| 4 | Perth, WA | 120-180ppm | Aquafiers / Desalination / Dams |
| 5 | Mt Gambier, SA | 150 -170 ppm | Limestone Rich Blue Lake |
| 6 | Adelaide, SA | 130 – 150 ppm | Murray River |
| 7 | Brisbane, QLD | 70 -100 ppm | Wivenhoe Dam |
| 8 | Townsville, QLD | 80 – 100 ppm | Ross River + Paluma Dam |
| 9 | Gold Coast, QLD | 60 -90 ppm | Hinze Dam / Desalination |
| 10 | Canberra, ACT | 40 -60 ppm | Dams + Murrumbidgee River |
Calcium hardness in fibreglass pools?
Some pool shops are unaware that the calcium levels in fibreglass pools are very different to concrete pools. Consequently, some pool shops will incorrectly advise fibreglass customers to significantly increase the calcium levels in their water. This mistake happens because the water testing software used at pool shops is primarily designed for concrete pools rather than fibreglass. Remember, most concrete pools have a suggested calcium range of 200-300ppm while fibreglass pools are often much lower – usually around 120ppm.
So, to ensure that your water is at the right level, check the suggested calcium levels with your pool manufacturer. For example, the pool shown here is from a client who had heavy calcium build-up on their fibreglass pool from poor water balance. In addition to surface problems, excessive calcium in a fibreglass pool can clog salt cells, damage the heater, and obstruct pipework.
How to remove calcium from my pool surface?
If you spot calcium lumps or blotches in your pool, please don’t alter your calcium hardness to try and fix this issue. Often, some people advise that reducing your calcium hardness will dissolve the calcium on the pool surface. This is not true. For example, maintaining the calcium level at either extreme will only make the calcium formation worse, not better. Therefore, the only way to treat calcium formation on a pool surface is to either use a calcium dissolving compound or to drain and acid wash the pool.
If you have calcium lumps, streaks, or blotches forming in your pool, please get in touch with us for information. Remember, we can help you resolve these issues without draining your pool water.
Calcium hardness in MagnaPool systems
Inexperienced pool technicians and pool owners don’t understand that Magnapool calcium readings are unique. So, unlike a typical salt pool, ‘total calcium’ in MagnaPool includes the ‘magnesium salts’ which help run the MagnaPool system. When the calcium hardness is tested, these salts appear as part of the total calcium test result. Importantly, for MagnaPool systems, 70% of the ‘total hardness’ reading actually includes the magnesium salts and the calcium. Therefore, the tested calcium hardness reading for magnesium pools is substantially higher than typical salt pools.
Remember to allow for the magnesium content in the water when testing for calcium. For example, if your MagnaPool is running a measured calcium hardness of 200-250ppm, then your actual calcium level is way too low and you need to increase it right away! MagnaPool recommends a ‘total hardness’ level of around 800ppm compared to 200-300ppm for typical salt pools. Some pool shops now can test for ‘magnesium hardness’ which isolates the magnesium hardness from the calcium hardness which makes life a little easier.
References
Suggested calcium levels for MagnaPool
http://magnapool.com/wp-content/uploads/2016/11/How-to-maintain-your-MagnaPool.pdf
NSW Health
http://www.health.nsw.gov.au/environment/Publications/swimming-pool-and-spa-advisory-doc.pdf
High calcium levels damage fibreglass
https://www.swimuniversity.com/calcium-hardness-hot-tub/
Calcium hardness of Sydney tap water
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