When are Chemical Treatments Needed?
Over the years, chemical manufacturers have developed several forms of chelated copper compounds which lock in the copper ion and help prevent the formulation of copper carbonate to a large degree. These products control algae with better success than raw copper sulfate and copper-based product are the primary treatment tools used by many lake maintenance professionals. However, these products are still greatly affected by the pH of the water, and copper, as an element, continues to build up in the bottom sediment as treatments continue.
Chemical treatment programs in general are often affected by pH, water temperature, weather conditions, levels of organic materials in the water, and a variety of other conditions that are generally beyond the control of the pond-keeper. These drawbacks and variables, taken as a whole, can make the development of an effective chemical treatment program an extremely difficult, expensive and generally unsuccessful venture. The addition of beneficial microbes to your treatment program will help to control many of these factors and will stabilize the water chemistry both before and after chemicals are applied. By stabilizing the ecosystem, the microbes can also make chemical treatments more effective when they become necessary to treat specific aquatic growths.
The diagram above shows the chemical treatment cycle. As chemical treatments are added to the system, each dose kills the existing algae. The dead plant material drops to the bottom, where it begins to decompose. This decomposition frees up nutrients in the water, which are used to feed the next algae bloom. Throughout this cycle, nutrient levels, plus the levels of residual chemicals, build up BOD increases, oxygen levels decrease, robbing the lake of its ability to support fish and other aquatic life.
In time, anaerobic bacteria take over the decomposition of the dead organic material. Without oxygen these bacteria create methane gas and hydrogen sulfide, giving off foul, 'rotten egg' odors. Repeated chemical treatments are needed for the recurring algae blooms, while toxic chemicals continue to build up in the lake water and accumulate in the bottom sediment.
Despite all the time, effort and money invested, the lake gets worse instead of better. The water remains dark and murky and smells bad. The final stage of deterioration has been reached and eutrophication of the lake is completed.
While chemical treatments are only a temporary fix to algae growths, they are sometimes a necessary addition to an effective pond maintenance program. Chemical treatments should be used in conjunction with a ongoing bioaugmentation program to create a stable and balanced ecosystem. One could easily draw an analogy between chemical treatments in a pond and the prescribing of drugs and medications by a medical doctor. The best preventative treatment is to maintain a healthy ecosystem much like a healthy immune system, and chemicals like medical medications are used to correct a condition that grows beyond the systems ability to heal itself.
Where this analogy breaks down is in the results. While medical doctors can often cure disease with proper prescriptions, chemical treatments made to an aquatic ecosystem will often worsen the condition over all without ever addressing the root cause of the problem. Chemical treatments in a pond produce a predictable cycle of, growth, treatment, die-off, nutrient release and growth, with the overall condition degenerating with each repetition of the cycle. To compound this problem, oxygen is often severely depleted in the die-off phase, causing fish kills and further eutrophication of the pond environment. In contrast to this chemical treatment cycle, the addition of beneficial bacteria into the pond environment can help to stabilize the system so growths can not gain dominance in the system.
The original question in this chapter was, 'when are chemical treatments needed'? The short answer is only when absolutely necessary. Chemicals should be used to address algae and weed growths that are actively growing and still in the in the early stages of growth. As these plants increase they usually need more chemicals for treatment and the treatments get less effective. Repeating chemical treatments in follow-up applications may be needed for heavy growths. Many chemicals can be tank-mixed to used as combination treatments for a variety of plants or to increase the effectiveness of the treatment. You should always follow the label directions regarding treatment amounts and tank mixing. After weeds and algae are treated with chemicals to kill the plants, you should follow up with applications of beneficial bacteria to reduce excessive nutrient levels and stabilize the ecosystem.
The next section will help you identify the types of weeds in your pond and the correct treatment choices for each.
“We just throw some copper sulfate out there when the algae grows. That worked for a while, but the whole thing seems to be getting out of hand now.” Anonymous Pond Keeper
