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Underwater Aeration

Published: Tue, 16 Jul 2013 12:51:51
By: Michael Oleksak


Underwater aeration is essential in creating a beautiful pond. While a waterfall and/or fountain certainly helps and is aesthetically pleasing, underwater aeration will keep your water much clearer. Oxygen at the bottom will create an environment where the bacteria becomes aerobic instead of anaerobic.
Underwater Aeration

Our bacteria is facultative, which means it works with or without air. But, it works much faster with oxygen. Plus, your fish will like the environment better. Algae also lives at the bottom and it will not do well in the turbulent water. Algae enjoys stagnant water to prosper.

Just place a submersible pump on the pond bottom and run it at least a few hours every day. Obviously the more the better, but be careful not to let it clog where it may burn out.

Underwater airstones also work well. See your local pond/water garden/nursery dealer or favorite pond website to purchase the proper pump for your specific amount of water.

The key to maintaining sufficient dissolved oxygen content in your pond is to understand the basic relationship between water and oxygen. 

Oxygen is introduced into pond water through two primary ways:

  1. Surface exchange - Encourage proper gas exchange by keeping an area of open water. This open area should be free of vegetation or ice so surface water is exposed to fresh air. 
  2. Mixing - Water turbulence of any kind, regardless of how it's generated, significantly increases gas exchange. The fastest, easiest way to raise the oxygen level in your pond is with an aerator, fountain, or waterfall.

So how much air do you need?

Pond Volume in Gallons 1000 2000 3000 4000 5000 6000 7000 8000 9000 10,000
Liters of air/min required to maintain
Dissolved Oxygen at Koi Safe Levels
40 80 120 160 200 240 280 320 360 400

These numbers are intended as a guideline. Your application may vary according to stocking levels. (In general terms, 40lpm per 1000 gallons is a good rule of thumb.)


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