Pond aeration Pond aeration is essential for healthy and clear pond water. Enough oxygen in your pond is extremely important for your pond fish. Therefore always pay sufficient attention to the aeration of your pond. Your pond fish need at least 6mg / ltr oxygen. If this value falls below 5mg / ltr, your pond fish will become stressed. The moment your pond fish feel more stress, they use even more oxygen. And too little oxygen is obviously never good for your fish. You can easily test the oxygen values with special water tests. The Colombo Testlab Professional, for example, contains all water tests to properly monitor your pond water, including the oxygen values. In addition, pond aeration (through circulation) ensures that there are no stagnant corners in your pond. Extra oxygen also ensures that your pond is free from ice in the winter. In short, good pond aeration is indispensable.