How Much Pool Chlorine Do I Need? A Complete Guide to Pool Chlorine Dosing
How Much Pool Chlorine Do I Need? A Complete Guide to Pool Chlorine Dosing
If you've ever stood beside your swimming pool holding a bottle of chlorine and wondered:
“How much chlorine does my pool actually need?”
You're not alone.
One of the most common mistakes pool owners make is adding chlorine without first considering pool size, water condition and the strength of the chlorine they're using.
And here's the important bit:
More chlorine doesn't necessarily mean a cleaner pool.
The right chlorine dose depends on your pool and what you're trying to achieve.
In this guide, we'll explain how much Pool Guys Liquid Chlorine to use, when to use daily or weekly dosing, and when a shock treatment may be needed.
What does pool chlorine do?
Chlorine is used to sanitise swimming pool water by helping control bacteria and algae.
Pool Guys Liquid Chlorine is a fast-acting sanitiser for swimming pools and spa pools, designed to help keep water clean and clear.
Our professional-strength liquid chlorine contains 150 g/L available chlorine when packed and is made in New Zealand.
But before you reach for the bottle, there's one thing you need to know...
Don't guess. Test first.
The amount of chlorine your pool needs can depend on:
- The size of your pool
- Whether the pool is stabilised or unstabilised
- Your current chlorine level
- How frequently the pool is used
- Weather conditions
- The condition of the pool water
- Whether you're maintaining the pool or treating a problem
The Pool Guys chlorine label specifically recommends using a test kit or test strips to check chlorine and pH levels and adjusting the dose as required. If your local we offer FREE water testing too.
That's why there isn't one magic amount of chlorine that every pool needs.
How much Pool Guys Liquid Chlorine should I use?
All doses are in litres.
| Pool Capacity | Unstabilised Daily | Stabilised Daily | Weekly | Shock Dose |
|---|---|---|---|---|
| 5,000 L | 0.2 L | 0.1 L | 0.4 L | 0.6 L |
| 10,000 L | 0.3 L | 0.2 L | 0.5 L | 1.0 L |
| 20,000 L | 0.5 L | 0.3 L | 1.0 L | 1.5 L |
| 30,000 L | 0.7 L | 0.4 L | 1.5 L | 2.5 L |
| 40,000 L | 0.8 L | 0.5 L | 2.0 L | 3.0 L |
| 50,000 L | 1.1 L | 0.7 L | 2.0 L | 4.0 L |
| 60,000 L | 1.3 L | 0.8 L | 3.0 L | 4.5 L |
| 70,000 L | 1.5 L | 1.0 L | 3.5 L | 5.5 L |
| 80,000 L | 1.7 L | 1.1 L | 4.0 L | 6.0 L |
| 90,000 L | 2.0 L | 1.2 L | 4.5 L | 7.0 L |
| 100,000 L | 2.2 L | 1.3 L | 5.0 L | 7.5 L |
Important: These figures are based on average water conditions. Always test your pool water and adjust the dose as required.
What is the difference between daily, weekly and shock dosing?
This is where chlorine dosing can get confusing.
Daily chlorine dose
Daily dosing is designed to help maintain sanitisation of the pool under normal conditions.
The amount required depends on whether your pool is stabilised or unstabilised.
For example, according to the Pool Guys dosing table, a 40,000-litre pool has a daily dose of:
- 0.8 L for an unstabilised pool
- 0.5 L for a stabilised pool
Again, these are guide doses for average water conditions — test your water and adjust as required.
What does stabilised pool mean?
A stabilised pool contains an appropriate level of pool stabiliser, also known as cyanuric acid.
Stabiliser helps protect chlorine from being broken down by sunlight.
This is one reason the Pool Guys dosing table provides different doses for stabilised and unstabilised pools.
If you're not sure whether your pool is stabilised, test your water or ask the Pool Guys.
What is a weekly chlorine dose?
Weekly dosing provides a larger chlorine dose than the daily maintenance amount.
For example, for a 50,000-litre pool, the Pool Guys table gives a weekly dose of 2.0 litres.
However, remember that the label describes these as figures for average water conditions. Your actual chlorine requirement can vary, so test your water before dosing and adjust as required.
What is a chlorine shock treatment?
A chlorine shock treatment involves adding a higher dose of chlorine to the pool.
The Pool Guys Liquid Chlorine table provides a specific shock dose based on pool capacity.
For example:
20,000-litre pool → 1.5 L shock dose
40,000-litre pool → 3.0 L shock dose
60,000-litre pool → 4.5 L shock dose
100,000-litre pool → 7.5 L shock dose
Shock treatment can be useful when you're dealing with particular pool water problems, but don't automatically reach for a shock dose every time your water doesn't look perfect.
Test first and work out what your pool actually needs.
How much chlorine does a spa pool need?
Pool Guys Liquid Chlorine can also be used for spa pools.
The label gives a general spa pool dosage of:
50 mL daily
For heavy spa usage, such as hotels, the label specifies:
120 mL daily
As with swimming pools, water conditions and usage can affect chlorine demand, so testing your water remains important.
Why does my pool need more chlorine sometimes?
Your pool's chlorine demand isn't always the same.
You may notice your chlorine level drops more quickly when:
☀️ It's sunny
Sunlight can break down chlorine, particularly in an unstabilised pool.
🏊 Your pool is getting lots of use
Swimmers introduce contaminants such as sweat, oils, sunscreen and dirt into the water.
🌧️ You've had heavy rain
Rain can affect your pool water and may change the balance of your water.
🌿 You're dealing with algae
Algae can consume chlorine as you work to clear the pool.
💧 Your water chemistry isn't balanced
Chlorine is only one part of maintaining good pool water.
This is why simply adding more chlorine isn't always the answer.
Are you using too much chlorine?
This is the question we hear a lot.
And the answer is:
Possibly - but you can't know without testing.
If you're adding chlorine based on guesswork, you could be adding more than your pool needs.
On the other hand, if you're consistently under-dosing, your pool may not have enough chlorine to maintain proper sanitisation.
The goal isn't to use as much chlorine as possible.
The goal is to use the right amount for your pool and its current water conditions.
Pool Guys tip:
Don't guess. Test.
How do I calculate how much chlorine my pool needs?
Start by finding out how much water your pool holds.
For a simple rectangular pool:
Length × Width × Average Depth × 1,000 = Approximate pool volume in litres
For example:
8 m × 4 m × 1.5 m = 48 m³
That's approximately:
48,000 litres
You can then use the Pool Guys dosing table as a starting point and adjust according to your water test results.
If your pool has an unusual shape, varying depths, steps or other features, calculating the volume can be more complicated.
Not sure how many litres your pool holds?
Ask the Pool Guys to help.
Pool chlorine safety
Pool Guys Liquid Chlorine is a strong chemical product and needs to be handled carefully.
The product label classifies it as Corrosive, Class 8, and states that it can cause severe skin burns and eye damage. Keep it out of reach of children and follow the label directions carefully.
The label also states:
- Keep away from children
- Do not breathe mist, vapours or spray
- Wear protective gloves, clothing and eye/face protection
- Do not mix with acids or ammonia
- Store locked away, upright and in a cool, well-ventilated area
- Keep away from direct sunlight
- Follow the label directions when handling and disposing of the product
Never mix pool chemicals together.
Always read the product label before use.
The Pool Guys' simple chlorine routine
If you're looking after your pool yourself, keep it simple:
1. Test your water 🧪
Check your chlorine and pH levels regularly.
2. Know your pool volume 💧
You need to know how many litres your pool holds before you can accurately dose it.
3. Know your chlorine 🧴
Different chlorine products have different strengths. Always check the product you're using.
4. Dose according to your pool
Use the Pool Guys dosing table as your guide and adjust according to your water test results.
5. Keep an eye on your pool
Clear water doesn't mean you should stop testing, and cloudy or green water doesn't always mean you simply need more chlorine.
Pool Chlorine FAQs
How much chlorine should I add to my pool?
The amount depends on your pool size, whether it is stabilised or unstabilised, your current water conditions and the chlorine product you're using. For Pool Guys Liquid Chlorine, use the dosing table above as a guide and test your water before adjusting the dose.
How often should I add chlorine to my pool?
Chlorine requirements vary depending on pool usage, weather and water conditions. Pool Guys Liquid Chlorine provides daily and weekly dosing guidelines, but your water should be tested regularly so you can adjust the dose as required.
Can I put too much chlorine in my pool?
Yes. That's why it's important not to dose purely by guesswork. Test your water and follow the dosing instructions for your particular chlorine product.
How much chlorine does a spa pool need?
The Pool Guys Liquid Chlorine label gives a general dosage of 50 mL daily for spa pools, increasing to 120 mL daily for heavy usage such as hotels. Always test your water and follow the product label.
Need help with your pool?
Pool chemistry doesn't need to be complicated.
If you're in Wellington or the Hutt Valley and you're not sure how much chlorine your pool needs, the Pool Guys can help with water testing, chemical balancing and pool maintenance.
We also make our own range of pool and spa products right here in New Zealand - including our professional-strength Pool Guys Liquid Chlorine.
You enjoy the pool. We'll handle the pool stuff. 🏊♂️
Got a pool question? Ask the Pool Guys.