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.
The neutral point with PH is 7, at this point the hydrogen and hydroxel ions are at a balance, only when the hydroxel ions start to out number the hrogen ions will the water become more alkaline and the PH figure will rise.
PH testing can be done with simple test kits or specialist electronic meters. The majority of pond owners will use a simple liquid test, a small amount of pond water is added to a clear tube to which a reagent fluid is added ( amount varies according to the kit manufacturer), the sample will colourize and is then held up against a coloured card which indicates the PH level of the water sample.
The ideal PH levels for koi is between 7 and 8, a result of the water being neutral to slightly alkaline. The ideal PH for sturgeon is a range of 6.5 slightly acidic to a level of 8 slightly alkaline. Ponds will very rarely fall below the neutral range ( acidic) unless some form of pollution has occurred.
Slight PH fluctuations are common and generally cause no serious problem as the fluctuations are slow and the fish will acclimatise to these as long as the PH is monitored and does not remain at an above recommended level for to longer a period of time. In ponds with green water caused by an alge bloom the PH can fluctuate massivley from 7 - 11 in a 24 hour period, although this sounds extreme these fluctuations are temporary and should not prove serious to your fish.
