Why is my pool turning green?

Why is my pond turning green? Is the water in your pond not crystal clear? Do you dream of clear water? If your pond is green, don't worry. It's not necessarily a problem!

If you look at nearby lakes and rivers in spring and summer, you will notice that this phenomenon is very common. But why does the water in your pond turn green? And how can you check that it isn't "dirty"?

Why does my pond turn green in spring?

In warmer weather (especially in spring and summer), the water in ponds and natural swimming pools can turn green. This natural phenomenon can be caused by an excess of nutrients (overfeeding) or sunlight (not enough shade).

The algae that form due to too much sun are called Chlamydomonas. And even though some of these algae are familiar to most of us, such as Cladophora, having a green pond is not always very pleasant.

But don't worry: 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 is still advisable to test your water when it turns green. This way, you will know whether it needs treatment or not.

How to test the quality of the water in my pond?

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

• pH (hydrogen potential) - 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 levels - must not exceed 0.2 mg/L.

To determine these values, there are two main types of tests: drop tests or test strips. You can find them online or at your favorite garden center.

How can I prevent the water in my pond from turning green? [chemical-free techniques]

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

To start, avoid overfeeding your fish at all costs. Even though it is a real moment of pleasure and bonding for the whole family, stick to the actual needs of your fish population.

In addition, limit the amount of fertilizer that accidentally ends up in your pond water. Remove excess decaying plants, dead leaves, sludge, etc. However, make sure to leave some organic debris at the bottom of your pond to form the substrate.

This forms the basis of a stable and balanced environment for the pond's wildlife and plants. As in nature, the microorganisms and animals living in your pond need soil to thrive fully.

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

But be careful: do not shade your entire pond. Living creatures need light to live and grow peacefully.

And for more information on the maintenance and landscaping of outdoor ponds, we invite you to read our other blog posts!