Green swimming pool water is an indication of algae in the water. You can normally treat this with Anti-Algen, which often solves the problem satisfactorily. But besides this product, there are other remedies, depending on the cause of the algae. See my answers below concerning the possible causes and appropriate solutions.
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Causes of green swimming pool water
Main cause of green swimming pool water
There can be several causes of green water in a swimming pool. Often it is caused by too strong UV light in combination with the presence of food sources for algae, i.e. organic material, pollution, etc.).
The solution is simple. If your pH value is correct, then you only need to carry out a chlorine shock. You can perform a chlorine shock with either liquid chlorine or inorganic chlorine. The inorganic chlorine is the HTH Granular product which you can purchase from our webshop. Ordinary chlorine granules or tablets are not enough here, as they do not disinfect sufficiently, or combat algae.
Too little free chlorine can cause green water in a swimming pool
You can also get algae growth or green swimming pool water if there is too little free chlorine in your pool. Too little free chlorine is caused by too high a pH value (higher than 7.6 pH). When there is too little free chlorine, it cannot combat the algae or disinfect the water. At least not enough!
You can probably guess the solution. First add pH Min and once the pH value is right (between 7.2 and 7.6 pH), you can carry out a chlorine shock. You then repeat this with liquid chlorine (only available in our shops) or inorganic chlorine (HTH Granular).
Too much cyanuric acid
Green water in the swimming pool can also be the result of too much cyanuric acid. You won’t get this if you have enough free chlorine. The only solution for it is to add sufficient fresh water (not ground water) and then carry out a chlorine shock.
Fertilizer in the swimming pool
This last cause can turn your swimming pool water green overnight. Fertilizer, or fertilizer granules are e.g. the granules that you use to fertilize your lawn. It contains considerable amounts of nitrates and phosphates – ideal food for algae.
It is easy to avoid this, by taking care when you are fertilizing the lawn. The solution is to carry out a chlorine shock followed by a prolonged filtering – which we advise with every chlorine shock.
Avoiding green swimming pool water
It is important to deal with green water once you have it, but prevention is of course much better. Efficient swimming pool filtering plays a big part, and it is essential to operate this sufficiently.
HTH Floc Fix, a very good flocculant, helps to break up the smallest particles and allows you to remove them with the manual vacuum cleaner. It is very important to add a flocculating agent regularly, as this makes your swimming pool clearer, but also reduces the risk of algae growth, resulting in a green pool.
However, if you notice that your water is turning greener, add Anti-Algen as soon as possible. This may prevent the problem from occurring. Anti Algen is a product purely for disinfecting and destroying algae, so it will be a good help to you – it’s a good idea always to have a supply on hand.