Most Koi fish owners, because their pond is outside, don’t worry very much about the oxygen level in their ponds. This is a big mistake! They often forget about even simple Koi pond aeration. The fact is, the amount of dissolved oxygen in your pond is critical to the health of your fish. Don’t forget to check it often especially in the warm summer months.

There are several reasons why you need to pay attention to the oxygen level in the pond. First, its critical for the fish – this goes without saying. But it is also necessary for any vegetation you may have in the pond and most importantly for the critical chemical processes that go on including bacterial decomposition. Every pond has its own unique oxygen demand and it’s constantly changing. It’s affected by the number of fish and the amount of plant decomposition that goes on in the pond.

There is just so much oxygen that can be absorbed into water at any given time. It depends on factors such as the temperature of the water, movement of the water (aeration) and salinity. Since we’re talking about freshwater ponds here, salinity is not a factor to worry about.

As the temperature of the water rises, less oxygen can be absorbed. This is one reason Koi pond aeration becomes so critical in the warmer summer months. Keep a close eye on the dissolved oxygen levels in warm weather. Make sure you keep it at least between 5.0 and 5.5 mg per liter.

Find ways to keep the water moving. This will allow higher oxygen absorption rates. Oxygen levels can drop very quickly in water that is standing an become dangerous for your fish. Fountains placed in the pond, are a great way to keep the water moving.

Check the amount of algae growth in the pond. Algae will add oxygen during the day but will deplete oxygen during the night. Too much algae can be a real problem for several reasons but affecting the oxygen level is certainly an important one.

Remember to try and feed your fish during the cooler part of the day when it is hot. Fish that feed when it is warm utilize more oxygen than when it’s cooler. During the hot part of the day when the water is the warmest, the oxygen level will be lower. This combined with the feeding can bring the oxygen level down very quickly.

Make sure you plan for good aeration in planning a new pond or consider adding a fountain to an existing pond. This is one of the easiest ways to get good water circulation and add an attractive water feature at the same time.