This article was written by K.O.I. Instructor Ken Austin, for the SKAPA Newsletter.

I recently visited a Koi pond where the pond owner had installed a product marketed by Aquascape, Inc. known as the IonGen™ second-generation electronic water clarifier for Ponds, Pondless® Waterfalls and other decorative water features.  The pond owner was very satisfied with how this device had kept his pond algae free.

The IonGen™ consists of: 1) Control Panel – Touch pads that allow the user to adjust the level of copper ions produced based on the condition of the water feature; and 2) Probe – Copper bars are activated by the control panel and slowly dissolve into the water.  One of those bars has a positive electrical polarity and the other bar has a negative electrical polarity.  Electrical current flows from one bar to the next causing copper atoms to lose an electron, creating copper ions, which are released into the water.

Ion is a term that means a molecule missing an electron.  In this case, the molecule is copper.  Copper is toxic to fish.  It does not matter if it is molecular copper or ionic copper – both are toxic.  Copper is also toxic to algae.  That explains why this device is effective at eliminating algae in a Koi pond.  Copper has been used for many years as a chemical tool in freshwater farm ponds and aquaculture operations. It is both an effective algaecide and a parasite treatment. The problem with the use of copper is that there is a thin line that separates effective treatment levels from overdoses, which can kill fish.  Caution must be exercised due to the effects of copper on fish and other life in the water. If your water is low in alkalinity, or if you have a heavy algae bloom and no aeration, copper treatments are not recommended.

Aquascape recommends periodically testing the copper levels in the water, using the copper test kit included with the system, to monitor that the copper levels don’t exceed the recommended limits.   Recommended limits stated in the owner’s manual are 0.25 ppm.  Some of what we know about heavy metal, particularly copper, poisoning is:

• The toxicity of heavy metals increases with water temperature and this explains why some sick fish problems reoccur as the temperatures increase every spring.

• Heavy metals are more toxic in low pH conditions than high pH.

• General hardness levels also affect the toxicity of heavy metals, especially the toxicity of copper. The higher the calcium hardness level, the lower the toxic effect as the copper will precipitate out of the water at higher hardness levels.

• The effects of heavy metal exposure, especially copper, are additive. This simply means that with persistent exposure to heavy metals, both the physiological and physical conditions of the fish deteriorate. Heavy metal poisoning reduces the production of anti-body cells, thereby reducing the fish’s ability to fight off infection and it also reduces the mucous coat, possibly from constant irritation and this increases stress levels (and reduces immune system response). And heavy metals also directly affect the gills by first causing increased mucous production on the gills which can inhibit O2 uptake (more stress) and at higher toxic levels, destroy the gill tissue altogether.

• For fish suffering chronic metal poisoning, there is an inability for antibiotic injection regimens to work as we would expect them to work. Without removing the stressor (in this case heavy metal), no amount of antibiotics is going cure the bacterial infection.

Various experts (e.g. E. J. Noga, G. Post, and W. H. Wildgoose) recommend the safe copper concentrations in fish habitats to be no more than 0.002 - 0.006 ppm.  Note that this is a fraction of the amount of copper the Aquascape owner’s manual recommends (0.25 ppm).  Despite this apparent contradiction, Aquascape claims that the IonGen™, when used according to the manufacturer’s guidelines, is safe for fish.

One of the manufacturer’s guidelines is to maintain the alkalinity of the pond water between 100 and 250 ppm.  An alkalinity test kit is not provided with the system but is available at extra cost.  Alkalinity reduces (but does not neutralize) copper toxicity because alkalinity combines with copper to form less toxic compounds.  El Paso tap water often (but not always) has alkalinity levels above 100 ppm.  In between water changeouts, pond water loses its alkalinity over time because the bio-activity of the pond and its filter consumes alkalinity.  It takes constant monitoring and testing to maintain pond water to meet Aquascape’s alkalinity guidelines.

My conclusion about is that if your water conditions (temperature, pH, total alkalinity, and general hardness) remain at favorable levels, you could operate an IonGen™ at you pond for long periods of time and your fish would not have any symptoms of acute heavy metal toxicity.  The long term effects of chronic sub-lethal exposure to copper may not be obvious.  Other conditions like bacterial infections may mask the deteriorated immune system caused by the copper.  Also mucus coated and deteriorated gills caused by exposure to copper are symptoms of several diseases.

References:

Noga EJ: Fish Diseases, Diagnosis and Treatment, St. Louis, 1996

Post G, Textbook of Fish Health, Revised and Expanded Edition, Neptune City, NJ, THF Publications, 1987

Wildgoose WH, BSAVA Manual of Ornamental Fish, Second Ed., 2001

IonGen™ Installation Instructions & Maintenance Owner’s Manual, available at: https://www.aquascapeinc.com/upload/IonGen_Instructions.pdf