Is Enough Copper Too Much?

By Patrick Simmsgeiger, Founder of DWI

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Copper (Cu) products are able to control algae and cyanobacteria in aquatic environments by discouraging their life cycle. To kill 100% of a microorganism is impossible, so we toxify the water with trace elements of Cu until they retract colony growth. Chelated Cu products present an advantage in this control application compared to solid Copper-Sulfates. A further technology plateau exists in a double-chelated Cu molecule.

Many aquatic environments are rich in limestone, chalk or gypsum. Cu molecules attract these minerals like a magnet, but on a chemical level under ambient conditions. The resulting compound is a heavy Cu-Carbonate (Cu2CO3) which will fall or ‘precipitate’ out of the water column. Cu2CO3 molecules have a specific gravity greater than water so they sink into the sediment layer. This bonding diminishes the amount of Cu intended for the target species that live in the water column. Many applicators simply put more product into the water until the intended control is reached. Unchelated Cu can be toxic to many types of aquatic life when higher levels are used to compensate for precipitation. This old-school product also combines with free hydrogen ions in the water to form sulphuric acid (H2SO4), which is highly corrosive to lifeforms and equipment, and smells like rotten eggs. Needless to say, the application of a solid into the water column requires the crystal to dissolve, which may not occur before a portion of the product reaches the bottom. But tradition is difficult to overcome; many applicators like the feel and even the sound of solid Cu as it hits water.

Chelated Cu solutions do not combine as easily with the aqueous minerals present because a portion of the ions are already bonded. These liquid algaecides deliver better value by remaining suspended within the water column longer. A lower weight of Cu is needed for the same outcome compared to over-dosing with the blue crystal form. The fortunate side-effect is less precipitate at the bottom, which will need to be removed when toxicity is too high. Limnology science is discovering that lake bottoms may account for more than the majority of their own annual nutrient loading and toxicity issues. There is also an associated labor savings when using less product and chelated products are safer to handle because of the lower Cu molecular weight.

A double-chelated Cu formulation bonds most of the remaining ions, representing the latest in technology. One might ask, “How is the algae affected if most of the ions are already bonded?” Algae do not swim to or away from sources as they are not technically mobile. Rather than consume the algaecide, the presence of diffusing Cu interrupts the colony life-cycle of microorganisms. There is a lower incidence of Cu exhaustion while realizing the same level of control with chelated products. This allows the delivery of persistent Cu molecular-weight to the water column, from a product that is safer to apply and healthier for the biosphere, with other tertiary advantages.

Because a lower Cu concentration can be used, the result is better in the current season and over the long-term ecologically to the waterscape. Less Cu within the water is less toxic for fish and reduces plating-out and corrosion. This finer focus of Cu lasts longer, allowing for better control toward the 1.0ppm of Cu potable water limit (see EPA - Lead and Copper Rule, 1991). The user has more control and less labor in application and product handling/storage. In real-world experience, chelated Cu is targeted on the problem species at a higher ratio, decreasing the need for more efforts to interrupt the life-cycle of target species, also reducing long-term soil toxicity.

Not all chelator ingredients are the same. The best Cu products maintain potency in high alkalinity waters, even in colder temperatures. A good test is to freeze a gallon of product and then thaw it. If less than 100% returns to solution, then the formulation is inefficient and/or the chelator is not high quality. Microorganisms have different growth characteristics in different water chemistries. Performance should be consistent versus a broad range of species. The best product also has delivers control over a variety of geographic features with unique water chemistries, including ‘hard water’ environments.

Technology presents better tools, and chelated Cu is a prime example. Make sure your facility is using a highly controllable and cost-efficient compound. The availability of a double-chelated product allows ease of application, greater ppm control, and lower water toxicity as first-stage advantages. Overall Cu weight can be reduced, the algae will be kept to a healthy minimum, and long-term sediment cleaning events can be extended up to three times into the future. The results will speak for themselves while the application cost is equivalent to the older Cu products.

Chelated Copper vs. Standard Copper Sulfate

By Patrick Simmsgeiger, Founder of DWI

Copper has been used for centuries to make the waters of our world easier, and cheaper, for us to handle. In the Age of Sail, when ships were made of wood; copper plating was an innovation used to control the buildup of mussels, worms, and aquatic plants. In that era and before, people recognized the ability of copper to control aquatic life through contact. Jumping ahead to the modern era, copper is still prevalent, and it is still incredibly useful in handling aquatic organisms.

 In the aquatic management industry, a major debate now seems to be whether to use copper sulfate, or chelated copper sulfate compounds. Some question the point of chelated copper products, stating that it is just a new name for the same thing, and that the benefits touted by chelated copper manufacturers are exaggerated. This conversation is ongoing, and just as the aquatic environments companies treat are incredibly varied, so are the opinions of the people involved.

From here I am going to explain why I believe chelated copper sulfate is a superior formulation to standard copper sulfate.

Before really getting into the benefits of chelated copper, I think chelation deserves a short explanation for those unsure of what it actually is. The following is by no means a full explanation of the chemistry involved, but this will hopefully give an idea of what chelation is, and why it is relevant. Chelation is a process that utilizes molecules called ligands. These are molecules that specifically bind to metal ions, in this case, copper. These ligands form around the central copper atom, surrounding it, and in a sense protecting it from the environment for a time. There are many chemicals of varying strengths and solubility’s that can be used as ligands, and the selection differs by product. Translating this to algaecide effectiveness, ligands can increase the algaecide time of effect from a single day to a few weeks by allowing the gradual release of copper as the protective covering is slowly dissolved.

Now to get into the benefits behind chelated copper sulfate. As mentioned, the extended release time of the copper is one of the biggest advantages. Copper Sulfate crystals dissolve in solution, are sprayed on the target macrophyte or algae, and kill whatever they touch. However, this is as far as they go. Whatever isn’t in the direct application area can survive, and only the organic matter present at the time of application will to suffer the effects. Copper Sulfate is highly soluble, and without something to slow down the release process, the product has commonly worked to its’ full effect within 24 hours. Chelated copper sulfate has the massive advantage of not being immediately exposed to solution due to the ligands, and copper sulfates natural solubility is countered for a time.

Building on this, another benefit becomes clear from the release rate difference between the two. With chelated copper sulfate, you can apply metallic copper in smaller quantities, and less frequently. This makes sense when you consider the fact that non-chelated copper sulfate has generally run its course after a single day, and along with that, is really only affecting the areas of application as it descends through the water column. Chelated copper sulfate is also going to follow this similar path of descending to the bottom, but the difference is again made by the ligands. These compounds allow the product to stay suspended in solution for weeks at a time, releasing copper into the water column as the bonds are broken down. This allows for less applications as the copper is staying active longer, and has the chance be circulated around the application area. Instead of algae being killed for one day, algae will be affected for a longer duration as copper circulates through the system.

My final point is this; chelated copper sulfate lets you do more with less. No matter what your stance on copper products is, I think we can all agree that in a perfect world, we would never want to put heavy metals into our water. Some of you may have noticed, however, that we do not live in a perfect world, and copper is oftentimes a necessary tool to handle the problems aquatic environments face, be they natural or manmade.

When we use copper, applying the lowest amount for the greatest effect should always be the goal, and careless application is not acceptable in this day and age when so many resources are available to increase applicators knowledge and efficiency. By responsibly using chelated products we can make that much smaller of an impact on application sites and take less of a toll on the ecosystems we care for. Your sediment is not going to turn into toxic copper sludge from applying at recommended levels, but it is easy to figure that the less copper we introduce to the environment, the better. Chelated copper sulfate makes this option more realistic and is the product choice that I think should be made for those who work to preserve our waters.