Water Quality

The PH scale is used to register the degree of acidity or alkalinity of a body of water.
The PH scale ranges from 0 extremely acidic, to 14 being extremely alkaline and is based inversely on the concentration of hydrogen ions (H+) in the water in relation to the number of Hydroxel ions (OH-). The more hydrogen ions would make the water more acidic the water will be resulting in a low figured number result.

Koi are a very hardy fish having the ability to survive in a wide temperature range of 2-30 degrees C ( 36-85 degrees F ). In their native Japan the winters are very cold however they are also relatively short.
In Northern Europe and Northern America conditions can become extreme and are often a very long season of winter conditions. It is then under the extreme conditions that most problems may become present.

Natural fresh water carries a host of disolved substances, including both organic and in-organic componds that are picked up from the soil and rocks over which the water flows over and then enters as "run off " from the land in to lakes and rivers.
The mains water that we use to fill our ponds is neither sterile or distilled, and it retains the natural mixture of dissolved componds so essential for life. There are also additional componds that all water companies add such as chlorides, sulphates,carbonates, bicarbonates, magnesium, sodium and pottasium. These elements are litterally trace elements which very few contribute to 95% of the total concentration.

The amount of oxygen dissolving in water is dependant on the temperature of the water. This would mean that as temperature increases the maximum amount of oxygen that will dissolve decreases. As a fish keeper it is vital to understand the physical relationship between water and gas, and to be aware of the conditions that cause oxygen deficiancies which will cause stress to the fish in your pond. Koi and sturgeon need a minimum of 6mg per litre of oxygen in the water and this is achieved by the continuation of water flow via a pump and filter 24 hours a day 365 days of the year. No ponds should have their pumps turned off at night, it would amaze you how many people turn off the power to their ponds at night to save money only to wake to find alot of fatalities in their pond due to oxygen starvation.

The level of these three nitrogenous componds in the water is a critcal indicator of water conditions.
Ammonia (NH3) is a highly toxic gas produced by the decomposition of organic wastes and metabolic waste
produced by fish most of which is excreted via the gills. Ammonia is lethal in very low concentrations, depending on species and the levels of other water conditions levels of 0.2 - 0.5 mg per litre will kill fish fairly rapidly. Over longer periods one tenth of this concentration of ammonia can cause an increased susceptiability to disease, and in mind is that even one hundreth of the concentration can cause gill irritation.

In addition to dissolved compounds and organic molecules, natural fresh water also contains a wide range of microscopic living organisms, from tiny larve and protozoans to bacteria and viruses. The majority of these are non pathogenic, but some can cause can cause disease in both humans and animals. To render such waters for human consumption water companies treat it with suitable dissinfectants, the most common and widely used is chlorine.