Pond Shading Options For Limiting Green Water Algae

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I have to admit, sunny days make me happier.

But everything comes with a price they say, and sometimes the price you pay for ample sunlight is pond algae.

In the case of green water, which is caused by numerous single cell algae, the sun can play a major role in it’s growth.

After visiting with many pond owners over the years, when we get calls about green water, one of the common questions we’ll ask is, “does the pond get a lot of sun exposure?” The inevitable answer is almost always, “yes”. Other pond owners that had several ponds were often quick to point out that the ponds in some shade, were often clearer, and the pond’s in the sun were quite green.

Now don’t get me wrong, you want your pond to be exposed to a bit of sun…that’s just a good thing for desirable plants and your fish too, but too much of a good thing can often cause some problems.

Shading A Large Pond

In reality, green water (and sun exposure) can affect any size of pond. Large ponds that have the problem tend to be a bit more shallow, and they may have some stagnant water conditions. Large bodies of water can obviously be more challenging to shade than a small one, and about the best tool we have for that is pond dyes or tints.

Pond dye for large ponds usually comes in quart bottles which are concentrated formulas. Each quart will treat up to about an acre area that is four to six feet deep. Colors vary from blue, black, to a black/blue combination. The latter two colors tend to provide a bit more natural appearance in most ponds.

Pond dye may or may not be enough to clear a pond up of various problems but it does work well in conjunction with things like beneficial bacteria, aeration, or ultrasound, as well as many chemicals. In the end, it’s the best way to help limit sun exposure on big waters.

Shading Options For Water Gardens

When it comes to a small backyard pond, there are more options for providing shade.

Pond dye can be used in smaller ponds as well, but be advised, you’ll want to find a product specifically suited to smaller ponds. Don’t use a large pond product in a small pond as they’re often too concentrated.

Plants are probably my #1 favorite addition to a pond to provide some shading, namely because they also provide the added benefit of nutrient reduction too. Anything that can help out-compete the algae in some way is a good thing. Look for floating plants like lilies and lotus, or anything that can cover some of the surface.

And finally, physical structures can be a nice addition for shading a pond if you use a bit of creativity. For years I’ve suggested possibly using large umbrellas over very small ponds, or building a structure like a pergola or gazebo near the pond where doing so might provide some shade.

In recent weeks though, I’ve had several friends mention something called Shade Sails. Shade Sails provide a really attractive and relatively easy way to shade a pond or pool from the sun’s rays. Used as a single shade or in combination, these “tensioned fabric canopies” as they are called will block a reported 90 to 95% of the UV rays while remaining somewhat porous to rain.

You’ll find that Shade Sails come in a variety of shapes, colors and sizes and many leading department stores now carry them to some degree. Probably the widest selection that I’ve found along with the best prices is at ebay. I’ve included a link below that will show what’s available there right now.

Check out these great shade sails on Ebay.

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5 thoughts on “Pond Shading Options For Limiting Green Water Algae”

  1. I have a small pond, about 450 gallons. Even though it has been pretty hot, my pond water is crystal clear! I use the beneficial bacteria in the spring, as well as a small bale of barley straw. Works best in a laundry net bag, otherwise the fish like to pull the straw out. Then there are the water hyacinths! I buy 6 plants and wait for them to multiply. Happens pretty fast, once the water is 70 degrees or above. Just threw some out today, those 6 plants covered pretty much 3/4 of my pond. Before the plants really took off, I used “Green Clean” once. Very effective and does not harm the fish. Of course, I also clean my 2 filters every day, and skim out the sludge etc. with a swimming pool skimmer. Maybe my regimen will be helpful to some small pond owners…

  2. Good for you Hilde…it sounds like you’ve done some good things there and the pond is thriving. Love to hear that!


  3. Forgot one thing, to thank you Mark! Learned a lot from your site, and those that share what worked for them. Certainly made mistakes when I did not know any better and was a new pond owner. Takes time, well worth to keep an open mind and continue learning! Like to keep my fish happy and healthy…

    Thank you Mark for all you do!


  5. Jim…thanks very much for the kind words. Trust me, many people do ok without me, but I’m glad the tips have helped out.

    All the best,

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