Alk lowering but no PH

[CoralPlast]

I am dosing 3 part tropic marin, instead of theyr alk part i use randy-s carbonate recipe.

I was dosing daily 0.25dkh, 2.5ppm CA et the suggested amount of part C (calculating as suggested a+b/2)

After 3 weeks of not touching the tank i get home and KH is quite low but ph did not move.

Those are the value, how come PH did not muve but KH lowered a lot? it should not go toghether? (skimmer air intake is outrside of the house, during those 3 weeks no one was at home).

Any idea?

 

[Randy Holmes-Farley Verified Community Expert]

This is a duplicate thread, so I'm closing it.

The original is here:

https://www.reef2reef.com/threads/big-drop-in-alk-butr-not-in-ph-how-come.948091/#post-10770299