Explanation for the sudden ALK drop

[ReefBeta]

So I get this drop last night. Tests from Alkatronic. It was 8.4 at 5pm, but 8.0 at 11pm. Tests before and after are consistent for several tests as shown. ALK dosing has not been changed during that time. It's dosing kalk every 2 hours. I'm trying to theory craft what's the cause of that drop. Can spur of coral growth made such a drop over a 6 hour window? It sounds unlikely to me, but could be wrong?

Coincidentally, pH of the tank was raised up over 8.3 for the first time last afternoon, since I installed the CO2 scrubber. Not sure if it's related. Can it be result of precipitation caused by high pH? Didn't notice any unusual precipitation so far.


What could be the potential cause of such a drop of ALK in the otherwise stable environment?

 

[plankton]

What's your calcium and salinity level? If it gets too high it is possible to precipitate out Ca Carbonate and you will see drop in Ca, Alk and white power on side of sump, etc. Not saying that is what happened just agree that 0.4 sudden drop in alk is little odd especially if you run refug on alt cycle.