When maintaining a swimming pool in Cape Town or the Western Cape, one of the most overlooked but essential chemicals is pool stabiliser, also known as cyanuric acid (CYA). If your chlorine disappears too quickly under the South African sun, stabiliser is the solution.
This guide explains what pool stabiliser is, why it’s important, and how to calculate exactly how much to add using litres (the standard measurement in South Africa).
At Pools Reno, we offer expert swimming pool maintenance, chemical balancing, repairs, and renovations across Cape Town, Durbanville, Bellville, Somerset West, and beyond.
What Is Pool Stabiliser and Why Do You Need It?
Pool stabiliser (cyanuric acid) is a chemical that helps protect chlorine from being destroyed by the sun’s UV rays. In Cape Town, where summer temperatures often reach above 30°C, pools without stabiliser can lose up to 90% of chlorine in a single day.
Without stabiliser, you’ll spend more money on chlorine and risk unsafe water conditions. With the right amount, your chlorine lasts longer, keeping your pool clean, safe, and sparkling.
Recommended Stabiliser Levels for South African Pools
In South Africa, the National Spa and Pool Institute (NSPI) recommends the following stabiliser levels:
- Outdoor pools (Cape Town & Western Cape): 30 – 50 ppm (parts per million)
- Indoor pools: 0 – 10 ppm (not much stabiliser is needed)
- Saltwater pools: 60 – 80 ppm (higher stabiliser helps chlorine generated from salt last longer)
⚠️ Too much stabiliser can cause chlorine lock, where chlorine becomes less effective. Regular water testing is crucial.
Pool Stabiliser Calculator: How Much to Add?
The amount of stabiliser depends on your pool volume in litres. Here’s a quick calculation:
Formula:
10 grams of stabiliser per 1,000 litres of water increases CYA by 10 ppm.
Example:
If your pool holds 50,000 litres and your current stabiliser level is 0 ppm, and you want to reach 40 ppm:
- 50,000 L ÷ 1,000 = 50
- 50 × 40 = 2,000 g (2 kg of stabiliser needed)
👉 Always dissolve stabiliser in warm water before adding it to the pool, or use the skimmer sock method to prevent clumping.
Pool Sizes in Cape Town: Local Examples
Most residential pools in Cape Town range from 20,000 to 60,000 litres.
- Plunge pool (20,000 L): Needs about 800 g of stabiliser for 40 ppm
- Medium family pool (40,000 L): Needs about 1.6 kg for 40 ppm
- Large pool (60,000 L): Needs about 2.4 kg for 40 ppm
For exact dosing, use a pool water testing kit or bring a sample to your local pool shop in Bellville, Durbanville, or Somerset West.
Costs of Pool Stabiliser in South Africa
In 2024, cyanuric acid (stabiliser) costs between R90 – R120 per kg at most South African pool supply stores.
For a standard 40,000 L pool, expect to spend around R150 – R200 to get stabiliser levels right.
👉 Compared to the cost of wasted chlorine, stabiliser is a low-cost, high-value pool chemical.
How Often Should You Add Pool Stabiliser?
- Add stabiliser once per season, usually at the start of summer.
- Heavy rainfall in Cape Town winters can dilute stabiliser, requiring re-testing in spring.
- Backwashing your filter also lowers stabiliser levels.
Frequently Asked Questions: Pool Stabiliser in Cape Town
1. Can I add too much stabiliser?
Yes. Too much stabiliser can cause chlorine lock. If levels are above 80 ppm, partially drain and refill your pool with fresh water.
2. Is stabiliser safe for children and pets?
Once dissolved and circulated in the pool water, stabiliser is safe. Never allow direct access to the undissolved powder.
3. Can borehole or wellpoint water affect stabiliser levels?
Yes. Borehole water in Cape Town often contains metals and minerals but has no stabiliser, so you’ll need to add it when topping up your pool.
4. Do saltwater pools need stabiliser?
Absolutely. Saltwater pools in the Western Cape require higher levels (60–80 ppm) to protect chlorine generated by the chlorinator.
5. Where can I buy pool stabiliser in Cape Town?
You can buy stabiliser at most swimming pool supply shops in Bellville, Durbanville, or Somerset West, or from NSPI-registered suppliers.
Final Thoughts: Keep Your Pool Balanced and Sparkling
Using a pool stabiliser calculator ensures you add just the right amount of cyanuric acid to your pool. This small step saves you money on chlorine, keeps your water healthy, and extends the life of your pool system.
At Pools Reno, we offer:
- Pool chemical balancing and testing
- Weekly and monthly pool servicing in Cape Town
- Borehole and wellpoint water treatment for pools
- Pool renovations, resurfacing, and repairs
📞 Contact Pools Reno today for a free pool maintenance quote in Cape Town, Bellville, Durbanville, Somerset West, and surrounding suburbs.
Internal Links:
- Pool Chemical Balancing Services Cape Town
- Borehole & Wellpoint Water Treatment for Pools
- Swimming Pool Maintenance in Cape Town
