non-toxic care for algae in ponds

Asked June 20, 2014, 5:00 PM EDT

We have several large freshwater ponds in our subdivision that are growing large amounts of aquatic algae. This growth is becoming very unsightly and difficult for people to fish. We have had to turn off the fountain in the middle of one lake as it seems to make the algae grow faster. We are currently putting a non-toxic liquid in the ponds twice a week, but it doesn't seem to be working.
Please advise any alternative things we can put in the water or otherwise to alleviate this situation.
Thank you ...

Webb County Texas

2 Responses

The most effective and commonly utilized chemical controls for algae are algaecides containing copper such as copper sulfate or chelated copper complexes. Copper sulfate and chelated copper complexes have been demonstrated to provide excellent control (90% or greater) of all three types of algae when applied correctly at labelled rates. Copper sulfate and chelated copper complexes are contact herbicides that act as cell toxicants, and only kill algal cells that the copper contacts directly. Therefore, they must be sprayed or broadcast over the entire area where algae are growing to provide adequate control. In most cases, an aqueous form of copper is recommended because it is less complicated and easier to apply correctly. Effects of copper on algae can be observed in 3-10 days with the full effects of the treatment demonstrated in 4 to 6 weeks. Copper sulfate is generally sold as such, but may be sold under various trade names that do not immediately indicate the product is copper sulfate. Although granular forms such as crystalline copper sulfate may be cheaper, they require more effort because they must be dissolved in water prior to application by sprayer. Copper sulfate only works as long as the copper remains in the water column where it can come into contact with the algae. Crystals or pellets that are broadcast into a pond undissolved immediately sink to the bottom where they provide much lessened control of algae. Copper sulfate is not effective in hard or high alkalinity waters because it binds with the calcium in the water, forms a precipitate that drops out of the water column, and renders the copper ineffective as an algaecide. Extreme temperatures also affect the performance of copper sulfate. It does not work well in cold water and should be applied at temperatures greater than 60°F to achieve the desired results. Copper sulfate’s toxicity to fish increases with higher water temperatures, and it should not be applied during hot summer conditions. Chelated copper complexes are more commonly sold under trade names such as Cutrine Plus, Nautique, Komeen, etc., than is copper sulfate. Chelated copper complexes typically are available in aqueous forms that are sprayed over or injected under the pond surface where algae control is desired. Chelated copper can be used as an alternative to copper sulfate in many cases because unlike copper sulfate, chelated copper complexes precipitate at a much slower rate and are still potent in high alkalinity waters. They are also more effective in waters with colder temperatures. Chelated copper stays in solution and remains active for longer because it releases the copper ion more gradually than copper sulfate. Although chemical controls may seem more desirable due to their convenience and effectiveness, there are many factors that must be carefully considered before using chemical controls. Fortunately, at the time of this writing, copper sulfate and chelated copper complexes have no use restrictions and are safe for use to drink, swim, consume fish, water livestock and irrigate turf or crops. However, you should consult the label each time that you purchase copper sulfate, chelated copper complexes, or any other herbicide for that matter as labels can change. Copper concentrations should be limited to 1 ppm or less, no matter the water chemistry, in order to safeguard your fish. Therefore, it is necessary that an accurate determination be made of the water volume you will be treating to ensure that the concentration remains at a safe level. All copper compounds can be toxic to fish if they are used above the labeled rates. Be sure to test the pond water’s alkalinity and adjust copper treatments to alkalinity concentrations. Be very cautious when treating a pond with an alkalinity of less than 50 ppm, as copper can be toxic to fish. Never treat ponds with an alkalinity less than 20 ppm. Most importantly, follow all label instructions when applying chemical controls. Aquatic herbicides are not toxic to fish when properly applied according to the label. If you do not know the alkalinity of your water and want to have it tested, submit the appropriate water testing forms (http://soiltesting.tamu.edu/webpages/ forms.html) and your sample to Texas A&M Soil, Water, and Forage Testing Laboratory (http://soiltesting.tamu. edu/). Aside from algaecides containing copper, there are a few other herbicides options that provide good control (75 to 89%) of one or more types of algae. Diquat, flumioxazin, sodium carbonate peroxy-hydrate (best on blue-green algae) and endothall [only mono(N,N-dimethylalkylamine) salt of endothall formulations], provide good control of filamentous algae. Sodium carbonate peroxy-hydrate (best on blue-green algae) and endothall [only mono(N,N-dimethylalkylamine) salt of endothall formulations], provide good control of planktonic algae, while only endothall [only mono(N,N-dimethylalkylamine) salt of endothall formulations] provide good control of macroalgae. Because these herbicides only provide good, not excellent, control of algae, they are often used in combination with low concentrations of chelated copper complexes. This practice often results in a synergistic effect and the two herbicides combined provide much improved algal control than either herbicide alone. Diquat and endothall are two herbicides that are often mixed with copper compounds to enhance control of target species including algae. Before attempting this control method, you should be well versed on the specimen label, literature, chemistry, and legality of mixing various herbicides. States have various restrictions and you should consult with your state management agency.

Thank you Todd for the excellent advice. We have purchased the Pond Dye-Pure Blue Brand by Organic Pond. We look forward to receiving it and see what reaction it will have on the algae. We have spoken to the extension agent for TAMU and he plans to visit the property to view our problem as well.
Your post response to our question was very informative. Thank you !