“The Age Old Debate”

Here at Sweetwater Landscaping, we will always put gravel at the bottom of your koi pond and rock your entire pond in. You are probably wondering why we do this and why you pay for it. A short answer: It helps filter out fish waste by giving beneficial bacteria a home among the rocks.


Some contractors insist on leaving the black liner exposed at your bottom of the pond because gravel is hard to clean. They also insist gravel is harmful to the fish because the gravel apparently harbors anaerobic bacteria, and that it’ll interfere with the bottom drain. Our ponds do not have these issues because we build properly constructed eco-systems.


With twelve years in the pond construction business we see day in and day out the benefits of gravel in a pond. A properly built ecosystem pond will not only look better, but will ultimately be less maintenance day in and day out. Natural waterfalls, ponds and streams have rocks and gravel in them right?


The longer answer to why we put gravel in your pond…

1. It helps grow the good bacteria

  • Gravel allows the aerobic bacteria in your pond a place to settle and start filtering out debris like fish waste and plant debris.
  • Gravel and rock provide twelve times the surface area per square inch to aid the beneficial bacteria colonies growth.
  • Aerobic bacteria need the presence of ammonia and oxygen in your pond. Ammonia is produced by fish waste and decaying plant material. The oxygen needs to be continuously supplied to your pond constantly in order to keep the bacteria beneficial and not harmful. All ponds should run 24/7.
  • The gravel at the bottom of your pond actually allows a natural system of waste removal, almost creating a self-cleaning pond!
    • But a Caution: too much gravel on the bottom can cause problems, the gravel layer should only be 1” – 2” deep.


2. The pond is built in several levels (or shelves) to give structural integrity

  • By building the pond with shelves, and lining the shelves with larger rocks you gain more structural integrity. When a rubber-lined pond has nothing to support its structure the ground underneath can collapse. It collapses when water gets under the liner and swells.
    • By having shelves, when the ground swells it swells against the rocks which push back retaining the shape of your pond.
  • Shelves also provide varying heights within the pond for your plants.
  • Shelves are safer especially for children.
  • Shelves provide places in the pond to add ‘Fish Caves’ to help protect your fish from predators.
  • Gravel protects your liner from harmful UV rays. UV can deteriorate your liner in a similar way to how UV harms your skin.


unnamed-3(What the shelving looks like before being lined)


3. It just plain looks better!

  • Gravel looks a lot more natural than a black liner. You’ll start to notice when your liner is showing because of its unnatural look
  • Gravel for us is a must because it allows us to create a beautiful sustaining eco-system. Gravel allows our water features to be works of art your neighbors will be jealous of!