Can I use Vancouver tap water with semi-hydro?

[Ray]

Originally Posted by Clawhammer

Does anyone "rest" their water? My tap water (super pure PNW water) comes out of the tap between 7.5-7.8 before ferts. After resting 24 hours with aeration it is around 6.8 before ferts as CO2 is removed from the water by aeration. This effect is larger during the cold months as cold water absorbs more CO2.

Maybe I am misunderstanding, but the pH does not drop due to loss of CO2, it does so because water absorbs it, it dissociates and forms the weak, carbonic acid, H2CO3.

With the median concentration of CO2 in air being around 400 ppm, the equilibrium pH in pure water is about 5.3.

[Clawhammer]

Originally Posted by Ray

Maybe I am misunderstanding, but the pH does not drop due to loss of CO2, it does so because water absorbs it, it dissociates and forms the weak, carbonic acid, H2CO3.

With the median concentration of CO2 in air being around 400 ppm, the equilibrium pH in pure water is about 5.3.

Hi Ray, I stand corrected. I am gassing off something that causes my pH to drop almost a point in 24 hours. Could I be gassing off the Sodium hydroxide my city adds to the water to raise pH?