Acidic tap water, why?

[markl323]

I'm wondering if anyone else is experiencing this. My tap water pH level is about 7.0 but after a couple hours of areation, it goes up to 7.6-7.8 and stays there forever. My water reports say the pH should be around 7.8. The water is moderately soft. Could the absorbed CO2 be causing this?

[Carol_Roberts]

Yep. This is especially common in well water. The water is saturated with CO2. AS the fresh water is circulated in the tank it releases carbon dioxide. The period of time it takes to "stabilize" the pH depends on temperature and force of agitation. Warmer, forcefully agitated water stabilizes quicker than cold, slowly moving water.