For pond keepers, the most beautiful time of year is definitely during the warm season. As they sit at the edge of their pond with a cup of coffee, enthusiasts can enjoy the summery flowering of water and pond-side plants and take delight in observing the lively pondlife, including everything from koi to dragonflies. Unfortunately, rising temperatures often mean that all too soon algae will start to develop. Many consumers wonder how they can prevent this. This article looks into the frequent question of why Tetra does not use copper as an active ingredient in its anti-algae agents and explains why copper simply cannot be the agent of choice.
There are many well-known ways to prevent algae naturally, including carrying out partial water changes in a timely manner and removing mulm build-up from the pond bottom in the autumn. Measured feeding using high-quality feed products, such as those from Tetra Pond, also contributes to significantly reducing water contamination. Fast-growing underwater plants such as waterweed, mouse-ear chickweed and pondweed also compete with algae for nutrients, but they cannot be considered as a serious threat to algae in the springtime. However, despite the methods described above, once the water has turned green, large unsightly meadows of blanketweed have developed and there are problems with the water values, often the only solution is an algae controlling agent.
Copper can be found in natural surface waters, sometimes in high concentrations depending on the site, due to natural ore content and as a result of industrial and agricultural applications, or in the controversial antifouling paint used in shipbuilding. Water pipes, roof coverings and gutters also contribute to the copper content of water. For instance, using rainwater from copper guttering to fill garden ponds may mean that it contains a lethal load, as the acid rainwater is particularly good at releasing the dangerous copper ions. German legislative authorities are also well aware of the potential environmental threat posed by copper, hence the various laws, directives and regulations that strictly govern its use, such as the exemption regulation on rainwater. Tap water can also contain a significant volume of copper ions. According to Germany’s Drinking Water Ordinance (TVO), the acceptable limit value for copper is 2 mg/l and must not be exceeded between the water distribution company and the private water connection. However, it makes little sense to refer to the limit values dictated by the Drinking Water Ordinance when assessing the potential threat posed by copper in garden ponds, since these values have absolutely no relevance to the tolerance of aquatic animals. Nevertheless, it is important to monitor the concentration of metals in tap water when filling a garden pond or aquarium for the first time or when changing the water to ensure, by using for example Tetra AquaSafe, that the levels of metal that may well be safe and acceptable for humans are not damaging or even deadly for fish, crustaceans, small animals and microorganisms. Unbound copper, like all metals, is highly toxic for many aquatic organisms, but mainly for microorganisms (e.g. invertebrates, bacteria – even essential filter bacteria, algae and fungi). It is difficult if not impossible to try to decide between the advantages and disadvantages of using copper, i.e. balancing a desire to combat algae without damaging filter bacteria and daphnia.
Copper no longer plays a part in commercial fish farming due in part to the fact that it has been banned under the German Federal Water Act and corresponding regional laws. It is, however, still used in fishkeeping in a small number of pharmaceutical products. Copper sulphate is still commonly used in home-made chemicals, for example during the quarantine period for marine fish. However, this should be undertaken with the greatest level of care, as, on the one hand, it is very easy to exceed the dose and poison the fish and, on the other hand, the copper content needs to be continually measured to maintain the required effective concentration during the entire (sustained) treatment stage.
In addition to its use in pharmaceutical products, copper is also used to combat algae in garden ponds. There are several liquid agents and devices available on the market that can be used to release copper through electrolysis. It is however difficult to maintain the desired and/or required concentration of pure copper in a garden pond or aquarium for fighting and/or treating algae. Only unbound copper ions are capable of damaging algae and pathogens, as combined copper is harmless and ineffective. Measuring out and above all maintaining an effective dose is extremely difficult, almost impossible to calculate and to some extent even dangerous, due to copper’s strong bond with for example carbonates or, reversibly, with naturally occurring chelates and/or water treatment substances. Even measuring the active copper content can be problematic and there are many woeful tales to be found in internet forums on the unwanted re-release of the substance and its toxic effects. Fish tolerance limits for copper are not set in stone, but depend instead on the species of fish and its age, the length of exposure and the composition of the rest of the water, with the water hardness and the lowest carbonate hardness in particular tending to be the rule in garden ponds filled with algae. Furthermore, copper becomes more toxic when other dangerous metals are present regardless of the hardness level, effectively resulting in increased toxicity levels. The EC Freshwater Fish Directive (2006/44/EC) stipulates that water with a hardness of 5.6°dH (German hardness level) should contain a maximum of 0.04 mg/l = 40 µg/l of dissolved copper, whilst extremely soft water with a hardness level of less than 1°dH should contain no more than 0.005 mg/l = 5 µg/l.
These are only some of the valid reasons as to why Tetra has decided to refrain from using copper products for fighting algae and for other applications. In doing this, we are also adhering strictly to our company philosophy regarding environmental sustainability.
Tetra’s anti-algae products offer an alternative to “copper products” and even substances containing herbicides, which have been banned for use as plant protective agents in Germany for years. Tetra uses the active agent monolinuron, which directly attacks algae metabolisms and is available in the required effective concentration, without any unpleasant surprises. A well-renowned independent laboratory in Great Britain has confirmed that, provided the product is used accurately and according to strict safety margins, it will cause no disruptions or damage to the optimum biological balance between pond and aquarium life. A well-though-out coordination of the entire WaterCare range, alongside support from the industry and garden pond owners, for example through Tetra associate seminars and consumer brochures, all contribute to making garden ponds one of the most enjoyable pastimes, ensuring that you can relax and enjoy your self-made biotope.
Barron Benno ter Höfte
Head of Biological Quality Assurance