What if my koi are gasping?

Before we even start to think about the oxygen requirements of our koi, our pond is already full of oxygen consuming organisms.

• If a pond or filter are allowed to become oxygen deficient for any period of time, anaerobic conditions will prevail causing unstable water conditions and the tell-tale bad-egg smell.
• How do they work, and how can we measure how efficient and effective we are at adding extra aeration?
• Temperature: Oxygen behaves in a surprising way (compared to other solutes, such as salt) in that as the water temperature rises, its ability to dissolve oxygen reduces.
• At lower temperatures, water will dissolve greater levels of oxygen, making it more difficult for your aeration systems to completely saturate your water.
• Conversely, at high water temperatures, saturation can be achieved more easily as water can only hold reduced levels of DO.
• The most common form of air pump found around a koi pond is one that uses a rubber diaphragm.
• Oxygenated water that enters the pond at the waterfall will rarely sink to lower layers of water, being effective only at the surface.
• Furthermore, the physical work required to move water to oxygenate is significantly less efficient than moving air, especially when it only affects the upper layers of a pond.
• The large bubble size also means that only the upper layers of water receive the full benefit of the freshly oxygenated water.
• There are many different types of diffusers available to the koi keeper, ranging from the basic (and disposable) airstone to other larger (and permanent) self-cleaning diffusers.

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