Why is my pool turning green?

Why is my pool turning green? The water in your pond is not crystal clear? Do you dream of clear water? Your pool is green, don't worry. This is not necessarily a problem!

If you observe the lakes and rivers near your home in the spring and summer, you will find that this phenomenon is very common. But, why is the water in your pond turning green? And how to check that it is not “dirty”?

Why does my pond turn green in the spring?

On sunny days (especially in spring and summer) the water in natural pools and pools can turn green. This natural phenomenon can be caused by excess nutrients (overfeeding) or sunlight (not enough shade).

Algae that form due to too much sun are called Chlamydomonas. And while some of these algae are familiar to most of us, like Cladophora, having a green pond isn't always great.

But rest assured: these natural green algae will not endanger your fish. They will even shade your pond and protect their scales from the sun's rays. That said, it's still best to test your water when it turns green. This way you will know if it requires treatment or not.

How do I test the water quality in my pool?

It is very important, especially after a rainy winter, to test various parameters of the water in your pool:

• pH (potential hydrogen) - must be between 7 and 8;
• kH (carbonate hardness) - must be between 6° and 10°dH;
• gH (total hardness) - must be between 8° and 12° dH;
• Nitrite level - must not exceed 0.2 mg/L.

To define these values, two main types of tests exist: drop tests or strip tests. You can find it on the internet or at your favorite garden centre.

How can I prevent the water in my pond from turning green? [techniques without chemicals]

If your results are satisfactory, you can still take initiatives to prevent the water in your pond from turning too green.

For starters, avoid overfeeding your fish at all costs. Even if it represents a real moment of pleasure and sharing for the whole family, stick to the real needs of your fish population.

Also, limit the amount of fertilizer that inadvertently lands in your pond water. Remove excess decaying plants, dead leaves, silt, etc. On the other hand, be sure to let some organic debris sink to the bottom of your pond to form the substrate.

This represents the basis of a stable and balanced environment for the fauna and flora of the basin. As in nature, the microorganisms and animals that live in your pond need soil to thrive.

Finally, cover at least half the area with floating or large-leaved plants like water lilies. These plants compete with algae when it comes to shading the pond. It is therefore interesting to place some in order to limit the formation of green algae.

But be careful: do not create shade over your entire pond or basin. Living beings need light to evolve and grow peacefully.

And for more information on the maintenance and layout of outdoor pools, we invite you to consult our other blog articles!