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Frequently Asked Questions about Copper Ionization

Copper Ionization FAQs

Some Facts About Copper Ionization
As evidence of the effectiveness of copper ionization in water treatment rapidly builds, so does interest on the part of growers and food processors. Since copper ionization is a fairly recent arrival in the greenhouse industry, it is not surprising that growers have many questions. The following answers are from Lars Marohn, owner and operator of Lauren Hailey Technologies (LHT); Ratus Fischer of Fischer EcoWorks; and Aksel de Lasson, an Aqua-Hort developer and manufacturer from Denmark.

Why is copper ionization so frequently recommended these days?
Copper ionization fills an important niche in greenhouse water treatment. It makes sanitizing large volumes of water affordable, especially in recirculating systems. And copper ions travel throughout the water system, eliminating pathogens, biofilm and algae wherever they go.

Not long ago, some people called copper ionization “snake oil.” Why should I consider it now?
The former bad reputation was partially deserved. In early systems, the copper output was not controlled, so ion concentrations in the water fluctuated wildly. Many systems were undersized. For some growers it worked great, while others junked the systems. However, the new approach by Aqua-Hort® in Denmark has changed all that. Aqua-Hort systems automatically control the copper output according to the flow rate and the EC (conductivity) of the water. You set your desired copper ppm at the controller, and the machine consistently puts out the set concentration. Now, copper ionization results are predictable and reliable

Several companies offer copper ionization systems, with some considerably less expensive than others. Why should I not go with the cheapest one?
In practically all horticultural applications, the flow rate and EC of the water fluctuate. Aqua-Hort is the only automated copper-ionization system on the market that automatically reads and adjusts to the variations in GPM (flow) and EC, delivering the exact amount of copper programmed. To date, only the Aqua-Hort brand can do that. Cheaper systems cannot – no matter what the sales person may claim.

Each system needs to be designed for the specific intended application. Water from a pond is handled differently than a recirculating flood floor system. Low EC requires special copper electrodes. Flow rates and desired copper ion concentrations determine whether a system with a 5 or a 500 amp output is appropriate.  Systems can operate at line pressure, or under atmospheric pressure with open discharge into a tank. One-size-fits-all systems are not likely to produce the desired results.

Systems often appear cheap because they are undersized. It is crucial that the system be able to produce the necessary ppm copper at full water flow. In maintenance mode, you may run from 0.8 to 1.5 ppm. At start-up, until the pipes are free of biofilm, or to control algae, you need enough capacity to temporarily crank up to 2 or 3 ppm.

Should I apply the copper ions to the whole water system, or only to where the risk of disease is highest?
Generally, it is best to introduce the copper ions at the source of the water, so they act throughout the entire system. Unlike other disinfectants, you are able to take the full strength of the copper ions all the way to the plant roots with no toxic effects. This way, you are getting full benefits from the copper throughout the entire system. In any case, the whole water system needs to be looked at to find the most effective and affordable solutions.

How do the copper ions act on pathogens?
The positively charged copper ions are attracted to the negatively charged pathogens. Copper ions have the ability to pierce the protective outer membrane of a cell and disrupt enzyme balances, thereby killing bacteria and algae.

What pathogens do copper ions control, and at what ppm?
Pythium, Phytopthora, P.Ramorum, Clavibacteria, Xanthomonas, Agrobacterium, Ralstonia, Erwinia and others usually are controlled at 1 to 1.5 ppm. Depending on your disease issues, you may be able to use a lower maintenance level.

What initial system costs and operating costs should I expect?
Systems can range from $ 5,000 to $75,000, depending on GPM and the EC of the water. The annual electricity consumption of a mid-sized 100 gpm unit is around $75 per year.

How much supervision and maintenance do the systems require?
Once installed, the Aqua-Hort system runs on its own. In the beginning, until your maintenance levels are established, you will have to observe copper levels and their effects more closely. No regular maintenance is required. With low water flows, occasionally brushing sludge off the copper electrodes may be advised. The electrodes will have to be replaced about once a year.

Who already is using copper ionization and what are their experiences?
There are more than 450 installations worldwide, and more than 25 new ones in the United States over a recent two-year period. Customers range from operations under one acre to the largest operations, such as Metrolina Greenhouses. It seems fair to say that, across the board, growers find that copper ionization meets their expectation, which is the visible and economically significant reduction or elimination of disease issues. Where unsatisfactory results are reported, it likely turns out that incorrect information on water flow rates and quality were given to the manufacturer, or that instructions for installation or operation were not followed. As with any other greenhouse system, the learning never stops, and grower feedback helps fine-tune the design and use of the systems. However, copper ionization is definitely past the experimental phase and can be considered a reliable, safe and effective technology.

Do copper ions fight biofilm and prevent clogged nozzles?
Yes to both. Eliminating clogged emitter and nozzle problems alone can make a system pay for itself. Biofilm in pipes absorbs some of the copper ions. Until it is eliminated, copper ppm at the machine needs to be set higher to achieve the desired ppm at the nozzle.

What about controlling algae?
To kill and prevent algae, the copper ion concentration needs to be 2 to 3 ppm.  Depending on the situation, it may be sufficient to run the higher ppm only intermittently.

What about the claim that copper ionization promotes better root growth?
 Several independent studies show this to be true. An increase in calcium uptake has been noted. Return water in closed irrigation systems has shown fewer nutrients in the presence of copper ions, suggesting higher uptake by the root media and the plant.

How does copper ionization compare to chlorination, Zero-Tol™, UV, and ozone?
In many or even most cases, copper can replace those systems at lower long-term costs. That does not mean that the other methods do not have their place in the spectrum of water treatments. Should you encounter special disease issues, it is good to have the option of a shock treatment with a chemical oxidizer, such as Zero-Tol, which for constant application is very costly. UV does not add any substance to the water. It is affordable at low flow rates. Unlike copper ionization, it requires low turbidity and lacks a residual effect. Ozone adds beneficial oxygen to the water, but it gets more easily absorbed by organic matter in the water than copper ions. To keep ozone systems safe and effective, professional maintenance is essential. Chlorination is inexpensive to install, but needs close attention because the window between effectiveness and plant toxicity is much smaller than with copper ions. Although chlorination is safe when handled properly, many growers prefer less-toxic substances.

Can I combine copper ionization with other treatment methods?
Yes, with no known limitations. 

There must be drawbacks or problems. What are they?
Some iron chelates may degrade when exposed to copper ions in a low pH environment. Aqua-Hort provides specific recommendations. Aluminum piping and ionized water can create deposits, which can clog boom nozzles. In recirculating systems, the maintenance level of the copper ion output needs to be established by manual copper tests during the initial phase of use.

So how does the copper actually get into the water?
The water flows around a pair or multiple pairs of copper electrodes in the shape of rods or plates. A controlled DC voltage is applied to the electrodes. The flow of electricity expels copper atoms, which lack two electrons (= copper ions) from one electrode. They are carried away by the flow of the water before they can settle on the opposite electrode. To ensure even wear of all electrodes, the polarity of the voltage changes at intervals.

How does the system control the copper level?
Again, “cheap” systems do not control the copper level, which leads to unpredictable results. They are appropriate for swimming pools and other applications with consistent flow and EC, but are rarely sufficient for horticultural applications. In a controlled system, the electrical current (amps) between the electrodes is computed and adjusted according to the flow (GPM), the conductivity (EC) of the water, and the desired ppm copper. The amps flowing between the electrodes are proportional to the ppm copper released.

How long do copper ions last in the water?
Compared to oxidizing agents such as chlorine, free copper ions appear to be much more stable and long-lasting, especially when dissolved or when solid organic matter is present.  In a bottle of recirculated water from benches, the author found that free copper barely decreased for a month.

What happens to the copper ions once they’ve done their job?
Copper ions also are called “free copper.” Because of their missing electrons, they are unstable and in search of a new bond that supplies the missing electrons. Once the ions have bonded with a pathogen or a soil particle, the copper atoms become “bound” copper in regular copper compounds and a micronutrient for plants.

How great is the risk of plant toxicity if too much copper is applied, or if it accumulates?
Unlike chlorine, even a 10-fold overdose of copper ions has not shown toxic effects on plants. Excess copper is mostly absorbed by the growing media, especially peat. Plants take in only as much copper as they need. No excess concentrations in plant tissue have been found.

What about copper in the environment, in the run-off water?
The copper ion concentrations used are in the range of the federal limit of 1.3 ppm allowed for drinking water. Copper ions will be strongly absorbed by most soils and eventually become plant nutrients. Tests to be published in Germany show that no significant amounts of copper end up in the groundwater.

Can I use copper ionization to keep my pond clean?
European tests with floating copper ionization systems have shown promising results in preventing algae from growing. When 1 ppm of copper ions was applied to a small outdoor swimming pool, the water remained perfectly clear over the season, without the use of other treatments.

Why should I not use copper sulfate in my water system?
Copper ions created by electrolysis carry a higher charge and remain free ions for a longer time. In copper sulfate solutions, no free ions can be measured. For similar effect, copper sulfate reportedly costs more, and has more negative effects on the environment. While known to be effective in quickly killing algae in ponds, copper sulfate also can lead to oxygen-starved, foul-smelling dead zones.  

Are there other effects of copper ions?
Copper ionization in sprayers increases the efficacy of the applied agent. The ions are positively charged, which attracts them to the negatively charged plant. Spray drift can be reduced substantially. Another benefit is the de-scaling of the sprayer tank and lines. Tests at North Carolina State University show a 99.9% reduction in E. coli, a major concern in vegetable crops, food packing and processing.

Why should I believe the copper sales rep more than the reps of other methods, who also claim they solve all water problems?
No water treatment method is appropriate for all situations. Each has its niche and will work if designed and operated properly. Copper ionization covers a wider range of applications cost-effectively than most.  It is important to weigh the data and arguments, but the best insurance against poor choices still is talking to growers who already use the proposed systems in a comparable application.

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