Spring Koi Pond Opening & Biological Filtration Awakening
How to wake up your outdoor pond filtration, replace UV clarifier bulbs, and safely start feeding coldwater fish as temperatures rise.
As winter recedes and water temperatures climb above 50°F (10°C), outdoor ponds enter a delicate biological transition period. The immune systems of koi and goldfish reactivate slowly, while opportunistic parasites and bacteria thrive in warming waters.
A thorough spring service begins with vacuuming leaves, twigs, and bottom sludge that accumulated beneath winter pond netting. Decaying organic material releases hydrogen sulfide and consumes oxygen, creating toxic pockets if left undisturbed.
UV clarifier quartz sleeves must be acid-cleaned and the ultraviolet lamps replaced annually. Even if a UV bulb still glows blue, its germicidal wavelength output degrades significantly after 8,000 hours of continuous operation.
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