What is consuming my alk? precipitation or algae?

[KonradTO]

Hi everyone,
(sorry for the double thread but I wanted to separate questions about micro and alk).
I noticed that my 32g tank with macro only is consuming alk quite quickly. Alkalinity drops from 11 dkH to 7dkH in around 10 days. I don't have calcium based algae other than coralline, which is growing steadily but not like wildfire.
What could be consuming alkalinity? Last time I measured ph few weeks ago was around 7.7 after dosing sodium carbonate. Ca is within normal ranges and Mg is above 1500 ppm.
Could precipitation be the problem?

 

[Randy Holmes-Farley Verified Community Expert]

Algae does not consume alkalinity, unless it is a calcifying type such as halimeda.

Coralline can consume a lot (2 dKH in a soft coral tank, for example).

Rising nitrate depletes alk, as will many organisms (snails, urchins, etc.). Could be abiotic precipitation too.

 

[KonradTO]

Coralline can consume a lot (2 dKH in a soft coral tank, for example).
Rising nitrate depletes alk, as will many organisms (snails, urchins, etc.). Could be abiotic precipitation too.

I have coralline and snails, but I am not sure if this 0.3 dkH/day is a normal rate of consumption in a tank like mine.. I will check if there is any sign of precipitation

 

[Randy Holmes-Farley Verified Community Expert]

I have coralline and snails, but I am not sure if this 0.3 dkH/day is a normal rate of consumption in a tank like mine.. I will check if there is any sign of precipitation

That's a reasonable rate for most any tank.

 

[KonradTO]

That's a reasonable rate for most any tank.

Ok cool. I did not expect such a decrease without corals!