9 Tips For Effective Natural Pond Algae Control

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Written By Mark Washburn

Mark has 20 years of experience as a professional pond management consultant.

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For there remains, in this space-age universe, the possibility that man’s way, is not always the best – Rachel Carson

Seeing your backyard pond or water garden turn a murky green from an overgrowth of algae can be disheartening. While a limited amount of algae is normal, excessive pond algae can ruin the tranquil beauty of your water feature. Before reaching for harsh chemical algaecides, consider trying these natural methods to clear up pond algae blooms  and maintain clean water using gentle, eco-friendly solutions.

Time-Tested Proven Methods For Natural Pond Algae Control Without Chemicals

natural pond algae control is safe for fish and frogs

1. Barley Straw – A Natural Solution For Algae

Placing barley straw bales or loose straw in ponds provides natural algae control. As the straw slowly decomposes, it releases a chemical that inhibits algal growth.  Apply early in the season, as barley works better as a retardant to growth, rather than a treatment for existing algae.  Water temperatures should be around 70 degrees.  For best results, 2 to 3 bales per surface acre is recommended.  For smaller ponds, 10 to 25 grams of straw per square meter is an adequate dosage.

According to the Penn State University Extension Service, when applied at the proper time and rate, barley straw has been used successfully to control algae in all sizes of ponds.  Barley straw is one of the oldest remedies for algae control in ponds.

2. Use Hydrogen Peroxide To Manage Alga

Low concentrations of hydrogen peroxide added to ponds can treat existing algae by breaking it down through oxidation. The peroxide must come in direct contact with the algae in order to damage it.  Liquid applications (12% food-grade hydrogen peroxide is good) work best on surfaces.  Granulated products work best for algae that’s under the surface.  Carefully follow product instructions to avoid harming fish.  Repeat applications may be needed.

3. Aquatic Plants Enhance A Natural Pond

One of the long standing staples of sensible pond care, planting native aquatic plants in your pond can add beauty while helping absorb nutrients and prevent excessive algae growth. Floating plants like water lilies are a natural way to provide beneficial shade along with helping to keep your water clear and algae-free.  In effect, the desirable plants can outcompete algae for the available nutrients in the pond water.  Suggested coverage rates can range from 20% plant coverage up to 60% or more, depending on the nutrient levels in the pond, and how much sun exposure a pond may get on a daily basis.

4. Reduce Nutrients To Limit Algae Growth

Excess nutrients like phosphorus and nitrogen “fertilize” an algae bloom.  To manage these nutrients you want to do your best to identify where they are coming from.  Think about things like runoff from your yard or other nutrient-rich grounds.  Understand that decaying organic matter such as leaves that have fallen into the pond, or dead plants like algae, that sink to the bottom, will decay and become compost that can feed more algae growth.  In smaller ponds, fish can be a leading cause of high nutrients, if their size and number are too great for a pond’s water volume or they outpace the capacity of a pond filter to reduce their nutrient load.

5. Pond Dye Can Limit String Algae Growth

Dyes or microbial products that tint water can prevent algae by limiting sunlight penetration into the water column. They reduce, but don’t eliminate, the need for other control methods.  Available colors include blue, black-blue, and black tints.  Note that limiting photosynthesis in the pond may hinder the development of good algae that supports a healthy food chain for fish.

6. Mechanical Removal – Remove Pond Algae Manually

Manually removing string algae with rakes or other tools can be helpful.  For smaller ponds you can use a pond vacuum to suck up free-floating algae. Just don’t leave decaying algae in the pond.  Physical removal is the quickest way to get rid of algae in a pond and more importantly, all algae will eventually die, sink, and decay at the bottom, and this becomes like compost that will stimulate more algae growth in the future.  The cleaner you can keep your pond, the less prone it will be to algae outbreaks.

7. Beneficial Bacteria – Mother Nature’s Pond Algae Control

Adding microbe/bacteria products containing Bacillus species to ponds can aid in decomposing-excess organic material in your pond and the accumulated muck that typically makes any algae problem worse. These beneficial microbes can be a helpful tool for ongoing pond maintenance.  Not only do they help break down the builld up of decaying organics, but they are also very helpful in directly reducing nutrients from the water that provide fuel for agressive algae outbreaks.  If you want to emulate Mother Nature, microbes are the best way to clean your pond and keep it free of algae.

8. UV Clarifier For Clear Pond Water

A UV clarifier light kills algae spores as water flows through, preventing them from multiplying. Use in combination with other methods to maintain clear water long-term in your small pond.  Keep in mind that UV works best on single cell algae that create green water.  String or filamentous algae will not be affected.   But if your plagued with chronic green pond water, then a UV light may be the best solution to keep the water clear.

9. Pond Aeration Aides In Non-Chemical Pond Algae Control

If you have a fish pond it’s well understood that aeration can be very supportive of fish health.  But did you know it can also be one of the best algae control methods to start with?  Its true.  Whether you use aeration in the form of a fountain on the surface of the pond, or a diffused aerator which sits at the bottom, by increasing oxygen throughout the waterbody, nutrients like phosphorus and nitrogen will be better managed, because naturally occuring bacteria (which are aerobic) will simply work better.

Treating A Pond Naturally Is A Sensible First Step

By taking an integrated, natural approach to control rather than relying solely on algaecides, you can keep your backyard pond or water garden clean, healthy, and algae-free while protecting the ecosystem. Be patient, as natural treatments take time, and enjoy the clear water rewards!

There certainly may be cases where using an algaecide could make the most sense.  Or if other natural approaches haven’t produced the results you wanted.  Its understandable that you’d want to try something else.  So we aren’t ruling out chemicals completely.  Just know, that if your faced with the problem of algae in your pond, there is more than one way to deal with the problem.  In fact there are many natural ways that have been proven to work.  So considering all the benefits of natural treatments, and the potential undesirable side-effects of chemicals, to us it just makes sense to try the more holistic options first.

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