How to get rid of green pond water and String (Hair) algae

How to get rid of green pond water and String (Hair) algae

How to get rid of green pond water and String (Hair) algae

Every pond enthusiast has been there before. You've finished setting up your lovely new pond, you've beautified and customized it to your taste and maybe even added some Goldfish or Koi. Finally, you can sit back and enjoy the fruits of your labor (or maybe someone else' labor)...you will surely be the talk of the neighborhood now.

But alas, within a week your prized pond has turned an ominous green and you can barely see the residents within!

Gasp! What to do?

Fear not dear reader, for there is indeed multiple ways to fight this pest known as Algae. Algae is one of the most annoying pests a pond keeper has to deal with...the pain in their neck, the thorn in their side, the stone in their boot...you get the point.

What is Algae?

So what is this little green pest we call algae that has dared to infest your happy place? Algae is a simple plant organism which uses photosynthesis and combines water and carbon dioxide to produce energy and grow at an alarming rate. They do produce oxygen, which is a good thing, however when the sun goes down they use up all that oxygen to stay alive and expel carbon dioxide, effectively starving the pond and any other residents of vital oxygen.

Cheeky little beggars aren't they?

What type of Algae do I have?

A fantastic question dear reader, I'm so glad you asked!

There are essentially two types of algae that you will likely experience in your pond:

1. Green Water Algae: 

This algae are a single-celled organism which floats around in water gorging themselves on whatever food they can get their greedy little mitts on. They are so small they can pass straight through your filter whether its a high quality one or not, so simply adding a filter to ¥our pond will not get rid of green water algae. To give you an idea of how fast algae can grow, there can be as many as a few million algae cells per milliliter of pond water and they can double their numbers every few hours. If the conditions are perfect, algae will have no worries accomplishing these numbers in a very short amount of time.

2. String (Hair) Algae:

These guys will ling to just about anything in your pond and make your rocks, filter, plants etc look like they are growing a full and healthy head of hair. Something a few balding men probably wouldn't mind being able to do, however not something we want in our beautiful ponds. This algae will often seem to appear over night and quite literally out of nowhere and can double themselves in 24 hours.

String (Hair) Algae

Is Algae harmful to my fish?

Wonderful news! Algae wont harm or bother your fish at all. They wont mind whether they are swimming in water like pea soup, or water that looks like its just came out of a purifier. 

Great, so how do I get rid of Algae?

Another fantastic question!

Lets look at both how to get rid of algae and how to prevent algae from ever getting a foot hold in your pond.

1. Fish feeding

"If you love them...stop feeding them!"

I come from a good Italian family where at dinner time when I got half way through my meal, mum would completely refill my plate because I was always, "...so skinny!" Readers, when it comes to your fish you cannot be an Italian Mama! Fish are very good at finding food, especially in a pond. It is literally all they spend their days doing. They don't need to be fed by you every day. This causes them to become lazy and stop eating the natural foods and wastes they find in the pond. Consequently your filter will have to work harder to get rid of what they would usually eat. Another byproduct of you over feeding your residents is their waste. The more you feed them, the more waste they produce which provides all the nutrients algae will need to flourish. If you have plants in your pond, you only need to feed your fish every few days, if that!

2. Plant Life

This brings us to our next and very important point; plant life. The natural filtering effect that plants have on ponds is amazing!

Here's how the process works:

Fish eat food...fish produce waste (nutrients)...those nutrients make perfect meals for algae or plants...if you dont have enough plants in your pond, algae wins. If you have a sufficient number of plants, they eat up the nutrients and starve out the algae. Simple as that! Think of algae and plants as two boxers in a boxing ring constantly battling for food. Whichever one you have the most of takes the title belt.

Think about it...how many naturally formed ponds do you see with no plants and crystal clear water in nature? None, right? That's because nature got it right! Natural ponds will always have plenty of oxygenating plants eating up the nutrients and no Italian Mamas feeding the residents every day causing an overload of nutrients.

Plant life in an eco system pond

Because algae use photosynthesis to reproduce, any plants that can reduce direct sunlight in your pond are winners. A great example of these are water lilies and lotus. Some more examples of water plants that will help with algae problems are: Parrot's Feather, Anacharis and Hornwort.

Now as wonderful as it is to have plenty of algae battling water plants, I would caution you against having too many. As always, this is a balancing act and overpopulating your pond with plant life can cause brown or 'dirty' water due to too much decaying plant material.

Moderation dear reader, moderation! 

As you may expect, plants are not an overnight miracle cure for green water though. If you are expecting to plant a few water lilies one night and have crystal clear water the next morning you will be sorely disappointed. This will take some time, but I promise you the plants will do their job.

Plants in a Koi pond

A quick side note: If you have a Koi pond, you will need to explore other avenues to get rid of green water algae, as Koi have insatiable appetites for plant life and will usually shred and eat any greenery introduced within a few days. Koi will rarely harm other fish, but boy, oh boy do they like their salad. Think of them as very motivated vegetarians.

Koi eating watermelon plants

3. Water Treatments

Water treatments can be extremely effective options when algae has already moved in and taken up residence in your pond. There are a number of brands on the market that can be used to keep the green water algae and string (hair) algae population under control. The brand i use for both myself and my customers is AlgaeFix. This is not however, the be all end all solution. Use water treatments to get algae under control, but you will have to implement other methods to keep it under control. Make sure you pay close attention to the dosage instructions on the package/bottle to keep the environment safe for your fish.

4. Filtration and ultraviolet (UV) lights for green water

It is, in my humble opinion necessary in most instances to have a good quality filter and UV system like an Oase Filtral 5000 set up on any substantial pond, especially one that has fish in it. 

You may ask, "Why do I need an UV filter if my pond gets the sun during the day? Wont that do the same thing?"

Yet another fantastic question dear reader! You are a sharp one aren't you?

As any fourth-grader knows, the sun does indeed put out UV rays, however those rays actually aid algae in reproduction.

Isn't that cheeky?

The UV lights on filtration systems expose the algae to such high levels of UV that it kills the algae's ability to reproduce.

See? Now when your mother says, "Too much of a good thing is bad for you!" she doesn't seem so crazy, does she?

Once the algae has been dealt with by the UV light, it dies and clumps together causing it to be big enough for the filter to catch and remove from the water, or it falls to the bottom of the pond and forms a sludge that can easily be vacuumed out using something like an Oase Pond Vacuum.

5. String (Hair) Algae Control

There is alas, no magical wand, nor magic potion I can suggest for ye ol' string algae. Because it clings to surfaces on the pond, the UV filter cannot get to it, so it really comes down to having to get your hands dirty for this one. The most effective ways to get rid of these woeful wisps of hair algae are to scoop them out with a net, blast them loose with a garden hose (do be careful of your plant life though, no one likes getting a garden hose to the face), or pull them out by hand.

Some algae is OK!

So far, we have painted algae as the villain of the story and we cannot wait for the hero to swoop in, save the day, get the girl and ride off into the sunset, but be assured reader, that some algae is both ok and inevitable. Its actually a good source of food for your fish. You will never get your pond 100% algae free. There will always be some green on the walls and bottom of your pond. You may also find it on lights or pumps and filters. This is all normal. Your ultimate goal should be to get your water crystal clear. That is how you know you have a healthy pond.

Maintaining clear, algae free water

Remember readers, its all about balance. Too much of any one thing will throw your eco system out faster than a jack rabbit on a pogo stick. If you implement what we talked about above and maintain a sensible balance, youll have beautiful clear water, a stunning pond to show off to the Jones', and most importantly, super happy fish!


15th Mar 2017 Joel Forbes

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