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How To Get Rid Of Pond Algae (And Why You Shouldn’t Get Rid Of It All)

By August 12, 2021April 24th, 2024Ponds
pond with lilies and bamboo

August and algae are practically synonymous. As temperatures soar and summer heat mounts, it’s very easy to hit a tipping point where your pond morphs from a magical oasis into a green nightmare.

Before you panic, you should know that algae isn’t all bad – in fact, it’s necessary, and can be a sign of a good, healthy ecosystem. It’s only when it becomes excessive and threatens the balance of your pond that there can be a problem.

Take a moment right now and get to know algae a little better, why you need it, when you don’t, and how to both prevent it from getting out of hand in the first place, and to treat it if it does.

pond benchWhy All Algae Isn’t Bad

There are different types of algae, so understanding the type in your pond will go a long way to easing your mind. Generally speaking, there are two different types: suspended algae and string algae.

Suspended algae is known for giving ponds that greenish, murky look, but that isn’t necessarily a bad thing. Pond water isn’t meant to be crystal clear like a swimming pool. It’s a natural environment, after all, and algae provides both food and oxygen for the critters that live there.

You need some of this algae to keep fish healthy. It’s only when your pond becomes covered in that dreaded blue-green color that it can pose a threat, because as it dies off it will consume more oxygen than it produces.

Another type is string algae, which looks like you’d imagine – stringy strands of green that are notorious for winding themselves around rocks and plants and clogging up drains and filters. Some string algae is to be expected, so seeing it is not necessarily a cause for concern. String algae won’t turn your pond green, but too much of it is a real nuisance.

Now that you know that some algae is actually healthy for your pond, let’s talk about what happens when you end up with too much of a good thing.

pond waterfall logCauses And Treatments For Suspended Alga

When this otherwise beneficial organism turns your pond into pea soup, you know things have gone too far. Blooms of this type are usually caused by an imbalance in the ecosystem. Too much sunlight, or excess nutrients in the water due to overfeeding fish, stormwater runoff, or overcrowding, are all likely catalysts for suspended algae blooms.

And since suspended algae are single-celled organisms, they can easily slip through most filtration systems.

To combat the problem, you’ll need to add the right water treatments. Start by adding beneficial bacteria once a week. These bacteria populations will compete with algae for food, eventually starving it out.

Try an algaecide to eliminate blooms fairly quickly and efficiently. It’s safe for fish, plants, and other critters, and can be used in ponds, waterfalls, and fountains.

If green water persists (and remember, we’re not going for deep-lake Crystal clear!) then you may need to bring in a water clarifier, which uses a UV bulb to eliminate algae as it passes through the system.

Best Pond Plants For Healthy Water And A Gorgeous SeasonCauses And Treatments For String Algae

Like suspended algae, string algae is caused by an imbalance in your pond’s ecosystem. Too much sunlight and too many nutrients are both culprits in the proliferation of string algae.

And this pond pest is pretty hardy. Once it wraps its tentacle-like strings around rocks and plants, it can reproduce and become a frustration very quickly.

Again, just like suspended algae, string algae can be treated with an algaecide. There are different types of algaecides to choose from – liquids that can be mixed with water, or granular treatments that can sprinkled on surfaces like rocks to eliminate algae on contact.

There are also mechanical solutions, like Aquascape’s IonGen, which has an electron-producing probe that is effective at killing string algae.

##Avoiding The Green Stuff Altogether
When it comes to any pond ailment, prevention is your best defense. If you want to keep algae blooms at bay and make sure your pond’s ecosystem stays in balance, there are some preemptive steps you can take to keep algae at healthy levels.

It’s important to keep your pond appropriately shaded, especially under the intense summer sun. Algae loves the sun, so deprive it of a rich growing environment by protecting the surface of your pond from excess sunlight. It’s easy to do with strategic plantings, and will look even more beautiful, too.

Lotus, lilies and other floaters are excellent additions that will beautify your pond and make it harder for algae to thrive. And you may need more shade than you think – up to two-thirds of your pond should be shaded for maximum effect.

Marginal plants are another great addition, not only for their beauty but for their ability to out-compete algae for food. Pickerel, water iris, canna lily and others are perfect choices.

Be sure to feed fish appropriately – that means not too often, and not too much. Sprinkle enough food in your pond for fish to eat within five minutes or less, otherwise it is likely to sink to the bottom of the pond and decay, producing excess nutrients that algae will thrive on.

Proper water filtration is also key. High levels of ammonia and nitrogen can result from decaying food, fish waste, and runoff from lawns, to name a few culprits, resulting in a toxic environment for fish, and one in which algae thrives.

Mechanical and biological filters don’t always remove the algae, but they create a hostile environment for it grow in – and a far healthier one for fish.

pond plantsIf you notice a sudden bloom without an obvious explanation (like sun exposure or overfeeding fish) then be on the lookout for sources of possible chemical contamination. Pesticides, fertilizers and other chemicals can wash into your pond after a storm or during routine watering of your lawn, and quickly throw it out of balance.

Finally, be sure not to overcrowd your pond with fish. As a good rule of thumb, you should have at least ten gallons of water for every inch of fish. Remember, fish grow! So be smart about how many you add to your pond.

This all may sound like a lot, but maintaining a healthy pond is actually fairly simple. The proper combination of plants, fish, filtration and routine care will keep it balanced and beautiful with little effort on your part.

If you need help dealing with an algae bloom, or if you’d like to talk about keeping your pond healthy and clear in the first place, let us know.

We provide pond cleaning and maintenance services, fish care, and installations for filters and other equipment. You can find all of your pond care supplies at our Matawan showroom, so stop by to ask questions, bring photos of your pond if you have them, and one of our pond pros will be happy to help.