Management approaches generally focus on adjusting these three factors rather than treating algae as an isolated problem to eliminate outright. That might mean increasing floating or marginal plant cover for more shade, reviewing fish stocking levels against pond volume, or checking whether a filter is mature enough to be processing the nutrient load the pond is currently carrying. Barley straw and similar natural additions are sometimes used as part of a wider approach, though results vary by pond and are rarely instant.
The core issue is straightforward. Leaves and other organic matter that sink to the pond floor and are left there begin to decompose, and that decomposition releases nutrients into the water. Those nutrients do not disappear over winter, they sit in the pond ready to feed algae growth as soon as light levels and temperature rise again in spring. A pond that goes into winter with a thick layer of decomposing leaf matter on its base is, in effect, setting itself up for a harder algae season the following year.
Michael Wheat, Founder / Designer at Ponds by Michael Wheat, treats algae as diagnostic information about the pond's overall balance rather than a problem to mask, since the underlying cause tends to resurface if only the symptom is addressed.
Planting upkeep is usually the first component. Oxygenating and marginal plants need periodic thinning and dividing to stop them becoming overcrowded, which if left unchecked can tip a well-balanced pond towards poor water flow and reduced oxygen levels. Floating plants such as water lilies also need managing so their coverage stays proportional to the garden pond design and build service's surface area rather than taking over entirely.
Plant balance is the biggest lever. A well-planted pond uses oxygenating plants below the surface and marginal or floating plants around and across it to compete with algae for the light and nutrients that would otherwise feed a bloom. Ceratophyllum, commonly known as hornwort, and similar oxygenators are widely used because they grow without needing to be rooted in soil, making them easy to add or thin out as the balance shifts through the year. Floating cover from water lilies or similar plants reduces the light reaching the water column, which is one of the simplest non-chemical ways to keep algae in check.
None of this means every pond needs attention after every unusual spell of weather, most cope perfectly well, but weather extremes are exactly the kind of trigger that makes a documented, professional look worthwhile rather than waiting for a visible problem to appear months later. At around £150, a pond health audit is a proportionate way to get an honest answer on how the pond has actually fared, rather than guessing from a distance.