Oxygenating Your Pond

Oxygen plays a vital role in the health of your pond.  On the surface of the pond, oxygen enters the water as carbon dioxide and other harmful gasses escape.  Fish depend on oxygen in the water to survive and oxygen also plays a vital role in the biological filtration process to keep water clean and clear.   In hot weather, when water temperatures rise, the pond’s ability to hold oxygen in the water decreases.  During summer months it is especially important to ensure proper oxygenation in your garden pond.  Small ponds and ponds overstocked with fish are especially prone to oxygen shortages.  A sign of a pond that is lacking in oxygen is: fish “gasping” at the surface for air, odor, or excessive algae growth.  It’s important to maintain oxygenated water in your pond at all times.

The best way to aerate your pond is by increasing circulation and surface area. One of the best ways to do this is by adding a strong pump and a waterfall.  A waterfall filled with small rocks greatly increases the amount of surface area of the water, giving more opportunity to release harmful gasses while allowing more oxygen to enter the water. If you already have a water fall in place, consider adding a more powerful pump to your existing waterfall or add a second one.  Pond spitters are also a good way to circulate and oxygenate, plus they add another decorative dimension to the water garden.  Spitters and fountains also help increase the surface area of the pond by disturbing the water surface and creating splashes and ripples – all aiding in getting more water into contact with the air.

Another method, and perhaps the easiest, is to add an air pump.  Pond aerators push air through tubes to stones placed on the pond floor.  The air stones diffuse the air into tiny bubbles which rise up through the pond.  These are popular in indoor aquariums due to their benefits to the health of the ecosystem and work just as well outdoors.  A pond aerator is a great low cost investment benefiting both overall pond health and fish.

Oxygenating grasses work to produce lots of oxygen into the pond during the day.  In contrast they release carbon dioxide into the water at night.  While these plants are important to pond health, do not rely on them as the only source of oxygenation or allow them to take over too large of an area in the pond.

Other Tips to Maintain Oxygenated Water

  • Provide shade with plants in and around the pond; cool water holds more oxygen.  Trees and shrubs planted around the pond will help cast a shadow onto the pond while pond plants will provide shade directly at the pond surface. Be mindful how much of the surface is covered with pond plants – remember the surface is where oxygen enters the water!

  • Skim leaves and other debris from the pond surface regularly with a net or skimmer, as decaying matter decreases oxygen levels.  Any debris that sinks to the bottom of the pond should be removed with a net.

  • Clean filters regularly.  A clean filter works better providing needed circulation and removing waste and debris.