Most natural ponds don’t have much of a contour, so I don’t need it either. Rocks on the bottom are also okay and will not cause any problems.
While it may be true that most natural ponds don’t have much of a contour or even smooth surfaces, that doesn’t work for a man-made pond. Consider two reasons why.
- In a natural pond, the ratio of fish to gallons of water is very low. This reduces the waste produced overall in the pond, leading to very low amounts of ammonia and nitrites.
- Most natural ponds have creeks that flow into and out of the pond. This constantly refreshes the pond water, removing harmful chemicals that are produced from the fish waste and decaying organics.
Proper pond bottom contouring is another often overlooked design aspect. By contouring the bottom of your pond, you aid the bottom drains in keeping your pond waste and debris free. This prevents the buildup of harmful toxins in the pond, and from tannic acid (which comes from decomposing leaves) that will turn your pond brown.
Contour the bottom of your pond in a way that helps move waste and sunken debris toward the bottom drain. This requires a sloping shape around the bottom drains. Remember that with proper contouring, the effective diameter of a bottom drain is about seven feet. So with larger ponds you will need multiple bottom drains, creating a bowl or cone for each one.