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Why Is My Pond Water Green? (4 Common Causes)

Why Is My Pond Water Green? (4 Common Causes)

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As a pond owner, it’s a real bummer when you can’t see through the water and check on your favorite fishes. This usually happens when the pond water develops a cloudy green color.

Doesn’t sound so great, does it? It leaves you wondering why is pond water green and what can you do about it? And is there any way you can prevent this problem from happening again in the future?

In this post, we’ll answer all your hot questions to help you keep a clean and eye-pleasing pond. Let’s dive right in!

Why Is My Pond Water Green?

Having a pond can be a difficult business due to the fact that you need to be constantly maintaining it. A fish pond can get dirty pretty quickly, and while it doesn’t affect your fish, green water isn’t a pleasant sight.

Generally speaking, however, pond water going green typically means that the pool’s aquatic ecosystem has become unbalanced. This phenomenon is often referred to as pea-green soup or algae bloom.

With the above in mind, there are many factors behind why the water in your pond has gone green overnight. Below, we’ll go through the four main reasons that cause this issue.

1 – Algae

Fish ponds get filled with planktonic algae quite fast. It’s a form of free-floating bacteria that accumulates in the bottom of the pool with time. As a result, the water gradually starts to turn green.

Other forms of single-celled algae include Spongomonas, Euglena, and Chlamydomonas. No matter the name, though, this bacteria will feed on your fish’s waste and continue to build up.

Algae in your pond can become an uncontrollable problem if not addressed early. Luckily, it’s a pretty common issue that many pool owners face, meaning it’s easily handled.

2 – Sunlight

Ponds are better positioned away from direct sunlight since the sun helps aquatic bacteria grow faster. Not just that, but it also boosts the photosynthesis process of the pond’s organisms.

This kind of bacteria then begins feeding off any nutrients it comes across in your pool. As it grows, the water’s color will turn green in no time.

The best course of action here is to place the pond somewhere far from the sun. If you can’t, try adding enough pool plants to provide shade for your fish. This also helps keep sunlight away from the algae and bacteria.

3 – Overfeeding

Sometimes aquatic pet owners can get too excited with the fish food. Sticking to a schedule doesn’t always help either. Instead, you need to regularly keep an eye on your fish to ascertain whether or not it’s their mealtime.

Leftover fish food decomposes in the water. Consequently, the levels of nitrate and phosphate increase. Algae and bacteria will feed on the organic matter that’s left behind, turning your pond water green.

To avoid this issue, control the portion size of the fish food that you throw in. Keep meals a few minutes apart from each other just to make sure that everything gets eaten up.

4 – Fish Waste

It’s important that you fill your pond with the right number of fish. Otherwise, the water will fill up with heaps of fish waste that will then decompose and become food for the pool’s bacteria.

Additionally, leaving your pet’s waste behind will release nutrients that algae will later feed on. It also causes muck and sludge to form at the bottom of your pond—just another reason for the water to turn green.

Some fish can produce a substantial amount of waste as they grow, such as Koi and goldfish. Owning too many of them will increase the nitrate levels in the pond water, coloring it green.

How to Clean Green Pond Water

Keeping the above reasons in mind, the next step would be to figure out how to avoid the water in your pond from going green. Fortunately, it only takes a few simple steps and tricks to stop such a problem from happening.

Just be aware that if you overdo it, things can go south quite quickly. So, make sure that you apply the following with caution.

Water Filters

For pond owners, you have two options. Either you can set up a natural filtration system of plants or a biological filter pump.

If you’re going for the non-artificial option, you need enough space in the pool for it. Choose floating plants and irises. Their roots will reduce the amount of gunk in your water and help balance out the phosphate levels.

On the other hand, a water pump promotes the growth of good bacteria on its surface. They feed on the harmful algae to maintain the balance and stop the pond from going green.

Pond Plants

Adding plants to your pond is pretty beneficial for both you and your fish. They help create a more natural environment for your pets and release enough oxygen in their water; all while protecting them from the sun.

Go for floating plants, such as lilies, water cabbage, and lotus first. Besides being aesthetically pleasing, they minimize the junk in the pond and provide your fish with shady homes. It’s certainly better than installing filters in your pond.

Oxygenating aquatic plants, including hornwort and anacharis, are other great options to consider too. They filter out the waste and your pets will love nibbling on them.

Just remember to cover the top of the soil with rocks so algae don’t feed on the compost.

Final Thoughts

Why is pond water green? There are quite a few reasons that make your pond appear polluted. Not washing the bottom of the pond or airing it out regularly is among the most typical causes.

In other cases, overfeeding your fish or having too many in your pond will accumulate a lot of waste in the water. So, whatever the reason may be, you need to keep in mind how to properly take care of your pond.

That’s how you can guarantee crystal clear waters through which you can watch your fishies play and swim!


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