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Tricks to Prevent Green Pond Water

17th August

How to Prevent Green Pond Water

When you first dreamed up the idea of having the perfect pond, the last thing you would have imagined is for it to resemble something like pea soup! Unfortunately, that’s the reality for many pond keepers.

Green pond water is a common and recurring problem. Affecting both the appearance of ponds but the quality of the water they contain.

The good news is we’ve got 6 tips to help you prevent green pond water:

1. Keep a Good Amount of Fish

Anyone can appreciate that fish are a stunning pet and feature to have in a garden pond.

However, choosing the best fish to add to your pond is only half of the job. You have to add the right quantity. Those of you who are overstocked with the amount of you keep are destined for disaster! More fish in the pond means more natural biological processes. Fish then produce more faecal waste that forms the nutrients required for green water to occur.

How many fish can I have in my pond?

Research the amount of fish suitable for the volume of water in your pond. By keeping a decent amount of fish for the size of the pond, you prevent an overload of waste and reduce the nutrients available to trigger the growth of green water algae.

2. Don’t Overfeed Your Fish

Similar to overstocking fish. If you have a decent amount of stock but have a habit of overfeeding them, you’re likely to introduce excessive waste into your pond. Not only from the natural biological processes of fish but from the food that isn’t consumed.

What happens to fish food that’s not eaten?

Leftover fish food decomposes in the pond and turns into waste that also fuels the growth of green water. If you notice that your fish aren’t eating all the food you give them, reduce the amount and feed them enough to make sure there’s nothing left behind.

This is most likely to occur in your pond during winter months when fish have a reduced appetite.

3. Provide Some Degree of Shade

Green water causing algae are plants, and like any other plant, they love sunshine. This is bad news for any pond that isn’t sheltered from the sun. Sometimes building a pond with shade isn’t ideal, but there are still ways of providing some degree of it.

What pond plants are good for shade?

Aquatic plants such as water lilies which float on the surface are a great method. They provide partial shade to reduce sunlight exposure not only to algae but for fish such as Koi, which can be sensitive to sunburn. Plants such as; marsh marigold, water hyacinth, water forget-me-not, water mint or water lettuce.

Watch our video on How to Clear and Prevent Green Water in Ponds:

4. Use Beneficial Bacteria

As mentioned before, green water is caused by single-celled plant organisms called algae. This organism typically occurs when there is an imbalance (high amount) of nitrates and phosphate levels in pond water providing algae with the nutrients to grow and in perfect conditions, thrive! These nutrients are elevated via some of the points mentioned above, however, can be eliminated with the use of a beneficial bacteria treatment, such as Pond Klear and Filter Feed.

Pond Klear works by binding together and consuming the green algae particles, along with all the fish waste, dead leaves and organic matter that form the algae’s source of food. Pond Klear, therefore, prevents green water algae from growing.

Related Products

  • Front view of Envii Pond Klear - Pond water treatment from Envii

    Envii Pond Klear

    Clears green pond water and prevents algae.
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  • Front view of Envii Filter Feed

    Envii Filter Feed

    Use beneficial bacteria to clean filters and remove nitrites.
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5. Keep the Pond Aerated

Aeration devices are a useful way to increase the amount of oxygen in your pond that helps beneficial bacteria to break down and eliminate green water algae.

Does more oxygen reduce green water algae?

By increasing oxygen levels, they also promote the reduction of carbon dioxide. So, the algae have less food and grow at a slower rate. Great aeration device choices are water features such as waterfalls, fountains or even pump and filters.

6. Add Pond Plants

Having a sufficient amount of aquatic plants in your pond allows for more absorption of nitrates produced by fish from excrement and food waste. This leaves very little room for algae to feed off of the nitrates, as they thrive off of it. Floating plants will help provide shade and reduce sunlight to the pond to help control the growth of algae. Submerged plants release oxygen into the water and can be done so by attaching to a rock.

Examples of floating plants include: lilies and lotus’ and examples of submerged plants include: hornwort, parrot’s feather and anacharis (water weeds).

You know the saying… “Prevention is easier than…”

We hope you have found these tips helpful. Green water is an unsightly nightmare and preventing it is a much more straightforward and less time-consuming task that getting rid of it.

If you’re an experienced pond keeper, then you probably noticed that there was no mention of UV filters or better understood as UV clarifiers. That’s because there are several things you should consider before relying on pond UV filters to prevent green water.

To find out more, read: Essential Guide to Pond UV Lights.

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What is the best way of putting plant in a pond so the medium in the pots won’t be leaching outp