Why is my Water Feature Turning Green?

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I recently decided to recommission an old water feature by replacing it’s broken pump, giving it a thorough clean and filling it with fresh water. I was looking forward to evenings relaxing outside whilst listening to the soothing sound of gently flowing water, but along with that came another problem that I hadn’t forseen.

After a few short weeks I began to notice that the previously clear water had started become discoloured and the bottom of my water feature had started to turn green.

I began to do some research into what causes this, and the best ways to stop it from happening.

If your water feature turns green it indicates the presence of algae. Algae requires both warmth and light to thrive and feeds on nutrients from small particles and organic debris found within the water. Water features require regular maintenance to keep the growth of green algae at bay.

The growth of algae in my water feature accelerated a quite an alarming rate. Below is my water feature on 20 August. At this point it was showing the first signs of algae growth and the bottom of the water feature was beginning to take on a slight green tinge:

20 August : Water feature beginning to turn green at the bottom

Fast forward one week, and by 27 August the algae growth had got significantly worse and was now a much darker green. A layer of green sludge was starting to form over the bottom and sides of the water feature:

27 August : Things had got worse

What causes algae to grow?

Algae needs light, warmth, and also a source of nutrients to flourish. Without these, algae will not grow.

This means that if your water feature is located in a warm position that gets very high levels of direct sunlight it is far more likely to suffer from algae growth – especially during the summer months.

And there are many nutrients that can be found within water itself that algae can feed on. In the pictures above you can see organic debris such as leaves have already found their way into the water and these will act as an additional source of nutrition for the algae.

On top of that, slow moving water (as is found in many smaller water features) can in itself encourage a faster rate of algae growth.

How to beat the algae growth in your water feature – 5 top tips!

So if your once serene and relaxing water feature has turned into a slimy green headache, there are a few simple steps that you can take to help restore it to its former glory!

Take a look at these top 5 tips below to help keep algae growth in your water feature at bay!

1. Carry out a thorough clean

If you have an algae issue then the first thing to do is to give your water feature a thorough clean. After unplugging and draining down my water feature I was able to easily remove the pump in preparation for cleaning.

Because all water features are different, it is important to follow the manufacturer’s instructions when cleaning both your water feature and pump.

Because my pump was basically new it didn’t actually require any cleaning.

I set about cleaning the water feature itself using a cloth and a weak solution of warm water mixed with washing up liquid, rinsing it out fully before refilling and replacing the pump. I managed to get rid of all traces of the green algae using this method 🙂

For a few weeks after cleaning and refilling your water feature you may find that everything stays algae free, but in my experience simply cleaning the water feature alone, without taking further steps, could only be a very short term fix for the problem. You may find that the algae quickly begins to re grow and you may end up having to complete a full clean every 2 or 3 weeks to keep it in check.

The good news is that you can try following the next 4 steps to help stop this from happening!

2. Fill up with tap water

To minimise any potential algae growth, when refilling or topping up your water feature it is best to use clean tap water.

A mistake that some people make is to use either rain water or water from a barrel to fill up a water feature. This will make your water feature much more susceptible to algae, as the water used will be far more likely to hold contaminants such as organic matter which will then provide an abundant nutrient source for the algae to thrive.

3. Position the water feature out of direct sunlight

As we already know, exposure to sunlight and warm water promotes the growth of algae. Algae will grow fastest in the middle of summer when the temperatures and hours of sunlight tend to be higher.

My water feature was already positioned in a fairly shady location. But if your feature is in full sun it may be worth considering relocating it somewhere that offers more shade, somewhere that is not going to be exposed to direct sunlight all day long and where the overall temperature of the water will not be as high.

4. Use a water treatment

Water treatments are available to help suppress and clear algae growth in water features. I decided to take this option with my own water feature but was keen to use an environmentally friendly product. I eventually decided to use “Hydra Fountain Clear” water treatment.

Using this treatment was easy, after again cleaning and refilling with tap water, I just dosed the clean water as per the manufacturers instructions and after a few weeks I’m happy to say that the algae hasn’t come back.

Hydra Fountain Clear is available on Amazon below. It is safe for visiting animals and birds in its diluted form but should not be used in water systems with fish, plants and other aquatic life – always follow the instructions on the label!

5. Perform regular maintenance: keep the water clear of leaves and debris

Once you have a clean and algae – free water feature you can keep it in top condition by frequently removing debris such as leaves and other organic matter. This will minimise the nutrient content of the water and help discourage any more algae growth.

This is where I need to keep on top of things, because although my water feature is in a shaded position away from direct sunlight it is also below vegetation that can (and does) regularly drop leaves into the water. Without frequent clearing of the leaves the quality and cleanliness of the water will be compromised.

Regular pump maintenance as per manufacturer’s instructions is important too as leaves can potentially restrict pump operation.

If you are using a water treatment they may also specify a weekly maintenance dose (you will need check and follow the instructions on the label of the specific treatment that you are using). For example, the Hydra Fountain Clear treatment that I am using specifies a weekly dose to maintain a crystal clear water.

In Conclusion

By following these tips you should now have the tools in your armoury to help keep your water feature free of green algae. So you can now relax and enjoy the soothing effect of trickling crystal clear water in your garden!

If you are thinking of replacing your water feature, or adding additional water features to your outside space, why not check out the water features below on Amazon?

You can also view our other water feature related posts by clicking the links below:

Do water features attract rats?