When there is cloudiness in the garden pond, our first reaction is that it’s algae or swirled up excess mud at the bottom. And more often than not this assumption is correct and the cloudiness is caused by excess phosphates and insufficient maintenance (You can find more tips under: Zakalení vody ).
However, the problem shown in the picture is neither brown nor green, it’s milky. In newly established ponds, a bacterial bloom could be a reason, which can be caused by the explosive multiplication of bacteria. A mass reproduction of infusoria (paramecia and rotifers) could also be the cause.
In both scenarios, the use of a JBL PROCRISTAL UV-C unit ( UV-C čistička vody ) can be helpful and provide lasting clarification after only 36 hours.
However, in this case we were able to eliminate all the factors previously mentioned. So what else could it be?
The customer emptied his pond and completely refilled it. We generally advise against this step and recommend larger water changes with sludge extraction and cleaning. It is always advisable to divide the pond like a cake and clean it successively over several days.
The cause of the milky cloudiness
The customer's tap water had a pH value above 7.5 and a high carbonate hardness. The CO2 within escapes at the water surface and causes the pH value to rise.
When the CO2 content is reduced, less lime can be bound (carbonic acid equilibrium), so the lime precipitates and causes a milky cloudiness. In an aquarium, CO2 can be added to counteract this effect, which is also described as biogenic decalcification. Adding CO2 to a pond is not only unusual, it’s quite difficult.
Use a large glass vase to take water from the pond. This will enable you to see the discolouration and, with left to stand longer, the lime precipitation as well.
One way to remove cloudiness is to filter it mechanically. For this purpose, JBL SymecMicro a very fine filter fleece, can be used. It filters out all particles with a size of at least 1/1000 mm. However, it clogs very quickly and can only be used under observation.
Another possibility is to use JBL pH-Minus to lower the hardness and thus counteract the effect.
Have you been able to make similar observations in your pond? Which solutions brought the desired success? Just comment on this post with your experiences or questions.