Summer Guide – Keeping an Eye on Oxygen


The Summertime is arguably the most rewarding season for Koi pond owners.  Sunny weather and warm climates offer better opportunities to enjoy your pond and witness the true beauty of the Koi. With these benefits come a few potentially harmful side effects of the heat.

Ensure a healthy ecosystem for your Koi!

By performing regular maintenance on your Koi pond and staying vigilant for signs of distress, you can ensure a healthy ecosystem for your Koi!

“I have found a most beneficial and useful tip for any pond owner during these summer months is to provide adequate coverage and shade, all while enjoying your natural outdoor living space.” -Jeremy Pater, The Bloomin Bog Water Gardens

Monitoring the oxygen in your pond becomes especially important the hotter it gets. As water temperatures rise, fish become more active and algae blooms spout up, both causing faster oxygen depletion.

“Proper aeration is critical as the pond temperatures rise. A minimum saturation rate of 6ppm is essential for proper growth and appetite. This can be achieved with the use of air pumps, flow meters, and waterfalls,” said Mark Anderson from Vermont Koi and Goldfish. “Algae also consume a considerable amount of oxygen during the night, while producing carbon dioxide as waste. This can cause an oxygen crash overnight and a fish die off. Therefore controlling algae is very important in the summer months.”

Adding an aerator or waterfall to your pond can help keep the oxygen level up and assist in long-term algae maintenance, but choose what you add wisely. Whatever device you decide on should match up with your pond’s size – an under-sized aerator won’t give your pond the oxygen it needs, while one made for larger ponds will be a waste and could lead to oxygen supersaturation (a.k.a. gas-bubble disease).

“There are many issues that cause unsightly and poor water conditions. The biggest mistake is the lack of proper aeration. Nothing beats a good deep water aerator with ample flow rates and multiple diffusers.” -Laura Engelsman, Koi Nursery and Water Gardens

You always want to have a sufficient oxygen level in your pond, but monitoring it in warm weather is especially important. Why? Pond stratification – which can lead to uneven oxygen distribution throughout your pond. In cooler temperatures, oxygen stays relatively evenly distributed from the surface to bottom of the pond. But as the temperature rises, water near the top of the pond becomes warmer and lighter and water near the bottom becomes colder and denser.

Oxygen levels in the colder, denser water decreases because it is not in contact with the air and doesn’t circulate due to the difference in water densities. As waste that settles on the pond’s bottom decomposes, the oxygen level drops even more for the lower layer of water. If the pond water is stirred up – often by rain – the oxygen from the upper layer of water is released into the air and the entire pond’s oxygen level can drop to deadly levels.

When you spot signs of oxygen depletion there are a few things you can do. Adding an appropriately sized waterfall or aerator will help disrupt water stratification. Regular maintenance, including water changes and keeping the pond full, assist in spreading out oxygen in the water. Water hyacinth and lettuce, lilies, and other surface plants give you a 2-in-1 solution. Thanks to photosynthesis, the plants give off extra oxygen and they provide shade, helping to keep the water at a cooler, more even temperature. Just make sure to leave at least one-third of the pond’s surface open.

So how does Nualgi actually work? If you’re anything like Tom, you’ve likely struggled with getting the perfect pond. Nualgi Ponds works at the microscopic level, kick-starting the natural biological cycle in your pond by feeding healthy diatoms.

You can learn more about Diatoms by watching this video below. It’s fascinating!

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