Why is my Alk and CA consumption not equal?

[ranchhand02]

I have a JBJ nano cube 28 gallon tank that I use reef crystals salt on. The tank is 2 years old, and I have been relying on water changes to maintain my elements until recently. My Alk started dropping and I starting dosing to maintain the level. I am currently dosing 10ML a day to keep it around 9.5 DKH. My Mg is staying at 1450, and my calcium is staying at 430 without dosing either. Why is my alk being consumed at a much higher rate than my CA? I do a 10% water change every two weeks on the tank, and I am using a red sea titration kit for testing.

 

[miPapareef]

Most likely test error. Not human error, just the accuracy of the test and the small change that is actually happening.

I’d dose equally calcium and alkalinity. Then if over longer time period (bigger changes), calcium does become imbalanced then make dosing adjustments.

 

[kashman100]

Check your fresh mixed saltwater just to see what it is. Reef crystals has high Calcium

 

[-Alex-]

Alk can be also consumed by bacterial processes