A green pool means algae is growing faster than your sanitiser can kill it. It usually happens after a few hot days, heavy rain, a busy weekend, or when the chlorine or Pool Maxx 35 dose has been missed. The good news: a green pool can be brought back to clear water in a few days with the right steps in the right order.
Quick answer: test and fix the pH, shock the pool, add Algo Pro algaecide, brush, and run the filter non-stop. For a 50,000 litre chlorine pool that means roughly 275 to 550 g of Chloro Maxx 90 tablets as a shock and 1 kg of Algo Pro to start. Use our pool dose calculator for your exact pool size.
Why does pool water turn green?
- Too little sanitiser. When chlorine or Pool Maxx 35 runs low, algae spores from wind, rain and swimmers start to grow.
- Wrong pH. When pH is too high, chlorine works far less well, so algae gets a head start.
- Heat and sunlight. Algae grows fastest in warm, sunny weather, which is most of the year in India.
- Rain. Rain dilutes your chemicals and washes dirt and spores into the pool.
- Poor circulation. A pump that runs too few hours, or a dirty filter, leaves still corners where algae settles.
How to fix a green pool, step by step
1. Test the water
Dip a Pool Maxx 5-in-1 test strip to read pH and chlorine. You need these two numbers to choose the right doses.
2. Clean the filter and brush the pool
Backwash or rinse the filter, empty the skimmer baskets, and brush the walls, steps and floor. Brushing breaks up the algae so the chemicals can reach it.
3. Fix the pH
For a chlorine pool, bring pH to 7.2 to 7.6. If your pH reads 8.0, Pool Maxx pH Down at 1 litre per 1 lakh litres brings it to 7.6. If it reads 7.0, Pool Maxx pH Up at 1,020 g per 1 lakh litres brings it to 7.6. Never add more than half the dose at once; re-test after 2 hours.
4. Shock the pool
For chlorine pools, use one of these shock doses from the product labels:
- Chloro Maxx 90 Tablets: 550 to 1,100 g per 1 lakh litres (5 to 10 ppm). Stay out of the pool until free chlorine is below 4 ppm, and re-check after 24 hours.
- Hypo Pool Shock: 5 to 8 times the regular dose, which is 750 g to 1.2 kg per 1 lakh litres. Dissolve it in a bucket of water first, run the filter 8 to 10 hours, and stay out for 4 to 6 hours.
If you use the chlorine-free Pool Maxx 35 instead, do not shock with chlorine. Keep pH at 6.5 to 7.0, add Pool Maxx 35 at 1 litre per 1 lakh litres every 24 hours until the water clears, and use Algo Pro as below.
5. Add Algo Pro algaecide
Algo Pro kills algae and helps stop it coming back. Start with 2 kg per 1 lakh litres, poured in with the filter running. Then add 500 g per 1 lakh litres every 3 to 5 days, more often in hot weather or heavy use.
6. Run the filter and clear what is left
Run the pump and filter non-stop until the water is clear, and backwash when the pressure rises. Dead algae can leave the water cloudy. If that happens, add Sparkle Maxx clarifier at 150 ml per 1 lakh litres. For heavy haze, Clear Maxx flocculant settles the dirt on the floor so you can vacuum it to waste. Ask our team for the Clear Maxx dose for your pool.
Doses for a 50,000 litre pool
| Product | Dose for 50,000 litres |
|---|---|
| Chloro Maxx 90 Tablets (shock) | 275 g to 550 g |
| or Hypo Pool Shock (shock) | 375 g to 600 g |
| Algo Pro, first dose | 1 kg |
| Algo Pro, every 3 to 5 days | 250 g |
| Sparkle Maxx, if cloudy after | 75 ml |
For other pool sizes, use the pool dose calculator. Choose "Water is green / algae".
How to stop your pool going green again
- Test pH and sanitiser at least twice a week, and after rain.
- Keep free chlorine at 1 to 3 ppm, or keep up the Pool Maxx 35 dose every 24 to 48 hours.
- Run the filter every day, and clean it regularly.
- Add Algo Pro every 3 to 5 days in hot weather.
- Shock after a party, heavy use or a big storm.
Common questions
How long does it take to clear a green pool?
Most green pools clear in 1 to 3 days of shock, algaecide and continuous filtering. Very cloudy water after the algae dies can take 2 to 3 days with Sparkle Maxx and the filter running.
Can I swim in a green pool?
No. Wait until the water is clear and free chlorine is back between 1 and 3 ppm. After a tablet shock, stay out until chlorine is below 4 ppm.
Can I use chlorine and Pool Maxx 35 together?
No. They are two different ways to sanitise. Do not add chlorine for 24 hours before using Pool Maxx 35, and the chlorine level should read zero when you add it.
Everything you need to fix a green pool is in the Starter Pool Care Kit, or browse all pool care products. Managing a hotel, club or society pool? Ask our pool team.
