How to clear green pool water

If your pool water has turned green, it'll be looking more like a duck pond than a swimming pool. In short, the colour and smell alone will be enough to put you off swimming! Been neglecting your pool care? Don't worry – it happens to the best of us. The key is to deal with the issue methodically which starts with identifying why your pool is off colour. We'll take you through a few of the main reasons why pool water turns so quickly and tell you exactly how to deal with the problem.

1. Firstly, there's no need to empty your pool. But before you set about treating the water, you'll have to clean your pool liner, pump and filtration system.

2. Use skimming nets to gather as much debris as you can – even if it's an unpleasantly slimy task! Then, connect a pool vacuum to your pump and use it to remove any remaining matter. Try to drain away any algae, impurities and floating debris. Essentially, you'll want to be removing about a third of the overall volume of your pool by cleaning the surface and bottom of your pool.

3. Next, clean away the water line which is probably stained green. Use a brush and a specialist pool cleaning product, and be careful not to damage the liner.

4. If your pool is equipped with a sand or cartridge filter, it's essential to give it a good clean. Rinse the filter out using plenty of water.

Restarting the filtration system

As soon as you've got the water level back up to the skimmers, you can move on to checking the quality of the water. Use a pool water tester to monitor the following parameters:

• pH level (ideally 7.2 and 7.6);

• Total alkalinity (ideally 80 to 120 ppm);

• Total hardness (ideally 100-300 ppm (mg/l)).

If you've got special disposable pre-filters for your skimmer baskets or pre-filter cartridges, now is the time to use them. This will prevent limescale buildup and reduce cleaning in the future.

Treating chlorinated water

Shock treatments for chlorinated water should be used at a ratio of 1 litre of product to every 10m3 of pool water. This type of product is often hydrogen peroxide-based and should be handled with care to avoid spraying or inhalation (gloves and goggles are recommended). It can be used on its own or in combination with a chlorine-based shock treatment depending on how discoloured the water is. Typically, your water should be clear and blue once more within 24 hours.

Treating non-chlorinated water

Shock treatments for non-chlorinated water are generally used in the same way and in the same concentrations as those for chlorinated water. The correct way to use these treatments is by pouring the liquid around the edge of the pool so it can be distributed throughout the pool by the inlets. The treatment takes about 48 hours to take effect, but you can start to use the pool in the meantime.

Whether you're dealing with a chlorine or non-chlorine pool it's important to wait a few days before taking additional measures as these products will unbalance your pool water as they work.

Flocculants are designed to help your filtration system work more effectively. They can be added directly to your skimmer baskets. Please note that the pH level of your water should be brought back to normal levels (7.2 - 7.6) before you use this type of product.

Algaecide should be added to the pool after each shock treatment and a clarifier can be used to prevent algae problems in future. It's also worth noting that you can invest in a pool chemical and water testing kit for everything you need to keep your water clear throughout the seasons.

Finally, be sure to wear protective gear (including gloves and goggles) when handling pool chemicals and always keep your pool products out of the reach of children.

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