Sandbed turning hard as rock- pH the cause ?

[ReefGeezer]

Yes, that is correct.

As pH rises from removing CO2, bicarbonate drops and carbonate rises and total alk is unchanged.
As pH falls from adding CO2, bicarbonate rises and carbonate drops and total alk is unchanged.

Thanks Randy. Your patience is appreciated.

 

[Randy Holmes-Farley Verified Community Expert]

You're welcome.

Happy Reefing.