Carbon question

[ScubaSteve]

It may have caused a swing in the pH. A pH swing is due to the carbon’s adsorption of chlorides, sulfates, nitrates, and other anions from the water, which caused a rise in the pH. Water pH remains elevated until the carbon’s pores become filled with these anions. Typically, 200 to 300 bed volumes of water must pass through carbon before pH drops to 8 or 8.5.

Typically we don't deal with large quantities of carbon with respect to out water volumes, so we don't often notice an effect, however, 2 cups may have been large enough to cause a swing.