why there is pH variation in water sample on keeping for some days??

Question

When pH of water sample was monitored,it was found that there is regular gradation in pH value>whats reason?
pH dropped from 7.1 to 3.9 in 6 days? pls answer with sufficent references..

Answer 1

The pH of a sample of water will change with time as the water absorbs carbon dioxide from the air to form carbonic acid. It is a slow reaction and dependent on temperature and other enviromental influences and the water samples buffering ability. You can do a little experiment to see for yourself using a magnetic stirrer. You will notice that upon vigorous stirring the pH of the water sample will drop quite a bit independent of the temp. You have sped up the reaction to form carbonic acid. Nearly pure CO2 is used in water treatment to adjust the pH for drinking water and in pH adjustment of wastewater for discharge.

Answer 2

At your present day water parameters, your most suitable selection will be African Rift Lake cichlids (maximum hardship-loose are from Lake Malawi & Tanganyika) and different fish from that area like cuckoo catfish. in case you decrease your pH to eight and slightly lower than, you would have better possibilities along with your swordtails, also mollies and platies.

Answer 3

That can not be possible. The PH level of water is 7.0 always.