Oxygen
Overview
The content of oxygen is of great importance for the biological processes in water and in the pond filter. Koi need oxygen to breathe through the gills. Furthermore, many biological processes require water oxygen. This is enriched by air feeding into the pond water. The oxygen content may not drop below 5 mg / l.
General
Oxygen (O2) is the most common element on Earth. Not only because oxygen is part
of the water. The proportion of oxygen in the air has about 21% volume percentage.
At 0 ° C and oxygen partial pressure of the air of 212 hPa in pure water, 14.16 mg / l oxygen
is dissolved. This, however, is strongly temperature dependent and is decreasing at higher
temperatures. Therefore, at higher temperatures in the water, the oxygen supply has to be increased.
Most living things need oxygen to live and grasp it by respiration. Fish are breathing via the respiratory gills,
when the oxygen enriched water is passing by. Hereby, oxygen of the water is absorbed and carbon dioxide is secreted.
Several bio-chemical processes in the water also need oxygen. Here you can mention the complex process of nitrification,
in which large quantities of oxygen are needed. With the help of oxygen micro-organisms reduce organic matter in water.
Consequently, organic contamination of can reduce its oxygen content.
Toxicity
Oxygen in high concentration is toxic; however such concentrations are not achieved in ponds.
Limit
A Koi pond for all transactions requires for Koi and bio-chemical processes an oxygen supply with a saturation of at least 5-6%. But rather > 7% is adequate.
