Co2 ph and Alkalinity ?

[Keithcorals]

Will a low ph caused by high co2 cause a noticeable increase in the rate alkalinity goes down ?

 

[Randy Holmes-Farley]

Low pH will reduce the rate of abiotic (nonbiological) precipitation of calcium carbonate, and it also reduces the rate at which many corals deposit calcium carbonate skeletons.

So yes, low pH from CO2 will reduce the demand for alkalinity in a reef aquarium.