Ponds near deciduous trees are naturally more exposed to this, and netting is one of the more straightforward ways to intercept leaves before they reach the water at all, provided it is checked and cleared regularly rather than left to sag under its own weight. For ponds without netting, or where some leaves inevitably get through, regular skimming through autumn keeps the volume of matter reaching the base to a minimum.
Across all three pond types, winter is a good time to think back over how the pond performed through the previous year and to plan for spring rather than to attempt any major work. Michael Wheat, Founder / Designer at Ponds by Michael Wheat, treats the winter months as a natural point to review a pond's condition ahead of the growing season, since problems that show up in spring often have their roots in decisions, or neglect, from the previous autumn.
UK weather has always been variable, but an unusually wet spring, a prolonged dry summer, or a hard cold snap can each put a pond under a different kind of pressure than it faces in an average year. After any of these, a pond health audit is a sensible way to check how the pond has actually coped, rather than assuming everything is fine simply because nothing looks obviously wrong.
Winter changes what a pond needs from its owner, and the right approach depends partly on what kind of pond it is. Swim ponds, wildlife ponds and koi ponds all slow down over winter, but the priorities for each shift slightly differently once temperatures drop.
For koi and ornamental ponds, the main winter concern is protecting fish through a period when they stop feeding almost entirely and become far less active, sitting low in the water for long stretches. Feeding should generally stop once water temperature falls consistently below around 10°C, since fish cannot digest food properly in cold water and uneaten food simply adds to nutrient load. The other key concern is ice. A pond that freezes solid across the whole surface stops gas exchange, which can allow harmful gases from decomposing matter at the base to build up under the ice. A small area kept open, whether through a floating de-icer or simply monitoring and addressing ice build-up, helps maintain that gas exchange through cold spells.
Read more from pond health audit service UK.