Chlorine Hot Tub Maintenance Guide & Schedule
Keep free chlorine at 3 ppm or more, test twice a day, and shock once a week
Chlorine kills bacteria quickly. This guide gives you a simple weekly routine: how much to add, when to test, and when to shock. The full range is in our Hot Tub Chemicals Guide.
Test before you bathe, and again after a long soak.
Your chlorine week
A chlorine routine has four parts: test, top up, shock weekly and refresh the water every couple of months. The CDC advises testing chlorine and pH at least twice a day, and more often when many people use the tub.1
| Task | What to aim for | How often |
|---|---|---|
| Free chlorine | At least 3 ppm.1 Our product pages aim for 3 to 5 mg/l.3 | Test at least twice a day1 |
| pH | 7.0 to 7.81 | With each chlorine test |
| Shock | Lifts the water and breaks down chloramines2 | Weekly, or after heavy use4 |
| Drain and refill | Clean, fresh water | About every two months2 |
Our pH guide covers the pH step, and our sanitiser guide compares chlorine with the other sanitisers.
How much chlorine to add
To raise the level by 1 mg/l, add 2 g of chlorine granules per 1,000 litres. As a guide, 10 ml of granules weighs about 10 g.3
Chlorine drops quickly in a hot tub, up to about four times faster than in a pool, so test before you add and test again after.2
| Tub size | To raise by 1 mg/l | To raise by 2 mg/l |
|---|---|---|
| 1,000 litres | 2 g | 4 g |
| 1,500 litres | 3 g | 6 g |
| 2,000 litres | 4 g | 8 g |
Example: a 1,500 litre tub reads 2 mg/l and you want 3. Add 3 g.
Add chlorine, step by step
Test first
Read chlorine and pH with a test strip before you add anything. See the 3-in-1 strips.6
Measure the dose
Use the table above, or the dose on your product label. Use a clean, dry spoon or scoop.3
Dissolve it in a bucket
Dissolve dry chemicals in a bucket of tub water first, and add the chemical to the water, not the water to the chemical.2
Wait, then test again
Wait at least 30 minutes after adding chemicals, then test. Get in once chlorine and pH are in range.2
Shock once a week
Why shock
Shocking oxidises the water. It breaks down chloramines, which are the cause of strong smells and stinging eyes, so your regular chlorine can do its job.2
The King County guide describes superchlorinating weekly to 10 ppm free chlorine, then letting the level fall to 3 to 6 ppm before you get in.2
What to use
Our Jacuzzi chlorine shock blend is dosed at 23 g per 1,000 litres, weekly or after heavy use, and you can use the tub about 20 minutes later.4
The Spa Fusion sachet treats up to 1,500 litres, and the tub is ready to use about an hour later.5
Our shock guide has the full steps.
What the water is telling you
Strong smell or stinging eyes
Chloramines are chlorine that has bound to contaminants. They signal too little free chlorine, and a shock treatment fixes them.2
Cloudy water
A shock treatment helps clear cloudy water and restores clarity.4
Our cloudy, foamy or green water guide covers the other causes.
Chlorine reading drops fast
Hot water uses chlorine quickly, and more bathers use it faster. Test before use and top up after a long session.2
Drain and refill every couple of months
Refresh the water
Drain, clean and refill about every two months. Adjust that for the size of your tub, your manufacturer's instructions and how often you use it.2
After a refill, bring chlorine to 3 to 6 ppm before you get in.2
Drain with care
Let the chlorine level fall before you drain. Avoid draining onto grass or shrubs when free chlorine is as high as 3 ppm, as it can harm plants.2
Your chlorine kit
Everything for the routine above. Every product is new and in stock now.
Jacuzzi Hot Tub Chlorine Granules
1 kg · £9.99
Your daily sanitiser. Dissolves quickly and raises chlorine faster than tablets.
Jacuzzi Hot Tub Chlorine Shock Blend
500 g · £15.99
Your weekly shock. Comes with a measuring spoon, and the tub is ready in about 20 minutes.
3-in-1 Pool and Hot Tub Test Strips
Pack of 50 · £4.99
Your daily test. Reads sanitiser, pH and total alkalinity in one dip.
Browse the full hot tub chlorine range.
Quick answers
Open a question to read the answer.
How much chlorine should a hot tub have?
At least 3 ppm of free chlorine, according to the CDC. Our product pages aim for 3 to 5 mg/l.
How often should I add chlorine?
It depends on how much you use the tub. Our chlorine granules page says it could be daily, every two to three days or weekly. Test the water and top up to stay at 3 ppm or above.
How long after adding chlorine can I get in?
Wait at least 30 minutes after adding chemicals, then test the water. Get in once the chlorine and pH readings are back in range.
How often should I shock a hot tub?
Weekly, or after heavy use. Our Jacuzzi chlorine shock blend page recommends a weekly treatment or one after heavy usage.
Why does my hot tub smell strongly of chlorine and sting my eyes?
Chloramines cause the smell and the stinging, and they mean the water needs more free chlorine. A shock treatment breaks them down so the chlorine works properly again.
Sources
- Centers for Disease Control and Prevention, Home pool and hot tub water treatment and testing (page updated 10 May 2024): hot tub chlorine minimum, pH and testing
- King County, Washington, Department of Public Health, Staying Happy and Healthy in Your Spa and Hot Tub, sixth edition (undated): chlorine levels, superchlorination, chloramines, draining and handling
- Jacuzzi, Hot Tub Chlorine Granules product page, sold by Outdoor Living: level and dose (current)
- Jacuzzi, Hot Tub Chlorine Shock Blend product page, sold by Outdoor Living: dose and use (current)
- AquaSParkle, Spa Fusion Aqua Sachet product page, sold by Outdoor Living: dose and use (current)
- Outdoor Living, 3-in-1 Pool and Hot Tub Test Strips product page: what the strips read (current)
Paul Margerison
Managing Director & Founder, Outdoor Living
A steady routine matters more than any one product: test, top up, and shock once a week.