Caliban07
Aquarium Advice Addict
Were you referencing just CO2 produced by the fish then? Sorry just trying to learn something new because I didn't see the op say they were injecting CO2 but then there was talk of CO2 off gassing.
OP also did not specify which time of day they were testing pH.
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I didn't reference anything .
Because tap water (cold especially) is under pressure and cool it holds more co2. I think some treatment facilities add co2 to reduce the pH after performing tasks that significantly increase it. So if you fill a cup with tap water it takes time for the co2 to 'gass off' thus as the co2 begins to reach atmospheric equilibrium the ph will rise (co2 dissolved in water forms carbonic acid H2CO3 and removal of this acid raises the pH)
Hope this helps.
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