Got Green Water?

13 Tips for Reducing and Preventing Green Water

how to get rid of green pond water

So you have a pond, and you love it. You have beautiful fish you love to watch cruise around the water. But now... the water is totally green and you can't see anything! You're starting to not love your pond so much. We hear this complaint in our store often, so if this sounds like you, just know you are not alone.

As we've said before, the easiest way to cure green water is to set up your pond correctly from the start. To see what we mean by that, read this article. But if you are way beyond the initial set up, read the steps below for some tips on what you can do now.

Before you begin, you must determine the cause of the green water. It can be single-celled algae or it could be tiny particulate (dead string or carpet algae) floating in the water. THIS IS VERY IMPORTANT. Take a sample of the pond water in a clear container and place it against a white background:

  • Does the water have a green color to it (see the photo below)? If so this article is for you... read on.
  • Does it lack the color but you can see little particles floating in the water? If you lack the color and see particulate, this post won't help you. You need to remove the floating debris from your water through cleaning or filtration. Check out this article for help in removing the debris.
green pond water
Yes, this is green water caused by suspended algae.

So you have determined the water is GREEN! Here we go...

1. Use BioClear and Clean Weekly or Increase Your Dosage if Needed -- Do this even when there isn't a problem to keep from having water clarity issues. Be proactive, not reactive. This product is a beneficial bacteria that will very effectively starve the algae making your water green.

clearing pond water with aerator
Look what a huge difference adding an aerator made to our Delight pond in the span of four days!

2. Add Supplemental Oxygen -- Bacteria as mentioned above is the key and it needs lots of oxygen all through the water column. Fountains and waterfalls only really oxygenate the area where the water falls back into the pond. Use an aerator to oxygenate the entire pond. Read more about aeration here.

3. Have Plenty of Fast-Growing, Nutrient-Eating Aquatic Plants -- WATER LILIES DON'T COUNT. Think floating plants, like water hyacinth and water lettuce. They spread very quickly using up lots of nutrients in the water also starving algae.

good fish food for clear pond water
Feeding with Cool Ponds Premium Fish Food will ensure your
 fish are digesting more food -- that means less waste in your water.

4. Change How You Feed Your Fish -- This is a big cause of green water. Just like a natural body of water fish can feed themselves just fine. Stop feeding them completely until your water clears. Then once the water is clear, only feed them Cool Ponds fish food (most commercial foods have tons of fillers that end up as waste in your pond that feeds algae). Feed them two or three times a week and only what they will eat in a minute or two. Yes, they will always appear and think that they're hungry. So does my husband--but he isn't really!

5. Increase Shade -- Here's where your water lilies can help. Floating plants make quick shade as well. Plants around the pond can help with shade too. Algae needs sunlight to thrive.

6. Stop Cleaning Your Biological Filter -- What??? When you clean your filter media, you kill all the beneficial bacteria in it... Yep, all that work just went literally down the drain. Only clean filter media when the water flow has started to slow down. If you have a biological waterfall, it should only be cleaned once or twice a year. Not sure what filter you have and how to clean it? We've got you covered.

7. Make Sure You Have 1-2" of River Rock in the Bottom of Your Pond -- I'm not going to debate the value of river rock in the bottom of the pond at this time (you are certainly welcome to look at our ponds and see the value for yourself). You can read our opinion on pond rock here. I will tell you that you need surfaces in your pond for all the awesome beneficial bacterial to grow on -- remember the bacteria that starves the algae? Having river rock in the bottom increases those surface areas exponentially! Use only river rock -- round pebbles 1" to 2" in diameter and a layer only 1-2" deep.

crystal clear pond
Your pond should have a lush, green layer of carpet algae just like the photo.
8. Keep the Carpet Algae -- Remember when your pond was brand new and you could see all the pretty rocks? Yeah, well that's the only time it will ever look like that! It's a pond -- it's supposed to look natural! You should have a slight green coating on ALL the surfaces under the water. This slight algae coating that we call carpet algae will do more for clearing your water than anything else! So stop trying to blast or scrub it off. It's good stuff!

9. Refrain from Draining and Refilling Your Pond -- Each time you do, you are starting the biological process over again. Drain your pond once or twice a year max in early spring or late fall. Rain water will flush your pond just like in a natural pond.

10. Keep Your Pond Clean -- If you have a sludge layer at the bottom of your pond, you will need to clean it to remove all of that. The sludge is only feeding more algae. Again, try to only clean your pond in the early spring or late fall. Also make sure to always remove any decaying debris from your pond. Trim back spend plant leaves. Install a net over your pond in the fall.

11. Improve Filtration -- A filter in the bottom of your pond doesn't do a whole lot. An external filter is better. The key is to get the junk out of your pond, not trap it in the bottom! 

12. Stop Using Algaecides -- Anything worth while is worth waiting for. Don't use any quick algaecides, or any algaecides at all really. They kill algae, which decays and feeds more algae. It's a cycle you don't want any part of. Plus we've heard many, many horror stories about how using algaecides have killed entire fish populations (the decaying algae sucks oxygen from the water).

13. Have Patience -- Try the remedies above knowing they won't work over night but will have longevity. Have patience now, and much, much less work later. You'll see!


Anonymous said…
Greeat article, just what I was looking for.
Anonymous said…
Very nice post. I just stumbled upon your blog and wanted
to mention that I have really enjoyed browsing your blog posts.
After all I will be subscribing to your rss feed and I am hoping
you write once more very soon!

Popular Posts