The temperatures are falling and German gardens have experienced their first ground frost. The neighbouring European countries have been affected as well. Although the sun is still very strong during the day and the temperatures are climbing towards the 20 ° C mark, the temperature drops rapidly during the night. The pond plants especially are wilting and dying. In our post " Preparations for the autumn - algae prevention " we gave you some valuable maintenance tips for the autumn, explained how to avoid algae problems in the following year and how to help to keep the pond algae-free to the end of the year.
There now follows a structured checklist of what to consider so that your fish stay healthy during the winter and start the next season well, and also what maintenance will prevent algae problems in the pond: Algae Control 1-2-3 algae free .
There was a time when many pond owners believed that with the falling temperatures, the pond season had ended and thus stopped feeding, even though the fish were still ready for some food intake, even if only in the deeper water zones. The consequence was often an occurrence of serious diseases during the spring. The reason for this was that the fish lacked the necessary energy and "substance" to survive a long winter.
It is therefore important not to interrupt the feeding, but just to adapt it to the temperature. You only need to suspend all feeding at temperatures below 5 °C .
The NEO Index will help you to select the right food. NEO stands for “Natural, Energy-Optimised nutrition”. In the cold season, e.g. in winter, fish need only half as much protein 2: 1 ( JBL PROPOND WINTER M ) as in summer 4:1 ( JBL PROPOND SUMMER M ). The swimming behaviour of the food needs to be changed too, as the fish swim less and less to the water surface. That’s why you need food that sinks, not floats, to avoid any unnecessary effort on the part of the fish, and encourage them to slowly come to rest at the bottom. The winter foods are easy to digest, even with low body activity. In the transition between summer heat and winter cold, an autumn food is recommended. It sinks to the ground and helps to make the animals "fat" and thus to survive the harsh winter. For this purpose, 10 % salmon oil is added to the JBL PROPOND AUTUMN M .
Everything worth knowing about fish nutrition in garden ponds can be found here: PROPOND® / NEO Index® .
In autumn and winter there are many and heavy rains. What does that mean for the pond?
The rainwater dilutes the pond water by a share which is not to be underestimated. Since it is "hardness-free", the stabilising carbonate hardness (KH) drops rapidly (below the minimum value of 4 °dKH) and this drop can lead to a sudden decrease in acidity because the pH is no longer sufficiently buffered. This effect can be counteracted with JBL StabiloPond Basis to reintroduce the minerals which have been consumed and diluted.
But heavy rainfall can cause yet another problem. Many ponds are designed so that nutrients can be flushed in from the surrounding area. During heavy rains, the water runs over the fertilized lawn or flower bed into the pond and introduces the fertilisers into the water - an ideal nutrient basis for algae growth. This is why the amount of water entering the pond from its surroundings should be kept as low as possible. Small structural changes can already make a difference. Under the subject of "algae" you will also learn how to bind the nutrients once they have entered.
Everything you need to know about water stability and rainfall can be found in this guide: Eau de pluie and in this blog post: Forte pluie – Attention aux paramètres d’eau de votre bassin .
If it freezes during the night and the temperature does not rise above 0 ° C during the day, permafrost can become a problem. A deep pond offers the fish an important refuge and a water temperature of 4 °C in the bottom area. A large volume of water has enough oxygen stored to ensure that even a long-lasting layer of ice cannot become a problem.
In addition to the complete freezing of shallow water ponds, a lack of oxygen is the most common cause of death for fish when the pond is completely covered with ice. A strong water surface movement can counteract the freezing. For this purpose, direct the filter outlet diagonally from below towards the water surface or let the water splash onto the surface from above. If the filter needs to be dismantled (find more about this in the section "technical items") a diaphragm pump/air pump ( JBL PondOxi-Set ) with an air stone can provide a high oxygen intake and a strong surface movement. If you are unable to adopt any technical measures you can keep the water surface ice-free by means of Styrofoam plates.
The low temperatures not only reduce the activity of the fish to a minimum, they also drastically slow down the work of important filter bacteria. For this reason, it is vital that the nutrient intake is reduced and the existing nutrients, for example in the sludge at the bottom, are removed by timely siphoning (at temperatures above 7 °C). JBL SediEX Pond can also help to reduce the bottom sludge.
Even when the hours of sunshine have reduced dramatically you are not safe from algae. High nutrient levels and a few sunshine hours are enough to cause floating algae, filamentous algae and other undesirable growth forms. Due to dying plants, algae and autumn leaves, the nutrient content in the water quickly increases to a high level (please check with JBL PROAQUATEST PO4 Phosphate Sensitiv ), as we have already explained in the post " Preparations for the autumn - algae prevention ". Through a permanent nutrient absorption with JBL PhosEX Pond filter in the filter or a selective addition of JBL PhosEX Pond Direct to bind large phosphate quantities you can counteract the undesirable growth of algae by depriving them of their means of growth.
Everything you need to know about algae control and prevention can be found here: Concept 1-2-3 sans algues .
When it comes to technical pond items, especially filtering items, many pond owners have heard the myth that it is time to put their filter system to sleep in autumn, at the same time as when they stop feeding their fish (both wrong!). When the activity of the bacteria decreases to a minimum at low temperatures, they are still performing their work, adjusted to the activity in the pond. The entire biosystem slows down its processes.
As long as the water is running through the filter, the filter media is not freezing, or the water flow has not come to a halt, the technical items sneed to remain in operation. In the case of heavy frost, they have to be uninstalled, as the water inside freezes and expands, leading to severe damage.
However, in many places, Germany included, their operation will be able to continue without interruption throughout the year. Water movement, as explained above, is beneficial. In addition, even when the biological activity is greatly reduced, nutrients will collect in the filter after you have mechanically removed "remnants" such as leaves, faeces, sludge etc. Now these can simply be removed from the pond by rinsing the filter media.
If you follow these basic principles, you’ll get through the cold season safely and not have any nasty surprises in the spring.
Do you have any questions or further care measures that you swear by? Let us know in the comments.