Where does the ALK go?

[Dom]

As I understand the pH scale (please correct me if I'm wrong), a pH reading of 7 is neutral.

As the pH reading tracks below 7 (neutral), the more acidic the water. And the more pH tracks above 7, the more base (alkaline) the water.

What goes on in our tanks that causes ALK to come down? How or why does ALK come down? I don't think it is consumable as say Calcium is, is it?

 

[nereefpat]

The terminology is confusing.

Alkalinity is actually a measurement of how well a solution resists acids. We use it as a way to measure carbonate (for our intents and purposes is the same as alk) in our tanks. Carbonate is consumed (along with Calcium) in our tanks by corals, coralline algae, snail shells, etc.

A solution can be alkaline (high pH) but not have high alkalinity.

Does that help?

 

[Dom]

The terminology is confusing.

Alkalinity is actually a measurement of how well a solution resists acids. We use it as a way to measure carbonate (for our intents and purposes is the same as alk) in our tanks. Carbonate is consumed (along with Calcium) in our tanks by corals, coralline algae, snail shells, etc.

A solution can be alkaline (high pH) but not have high alkalinity.

Does that help?

Yes it does, thank you!

I do have a great deal of coralline and my corals are thriving. I've always attributed that to uptake of calcium. I hadn't realized that carbonate (ALK) was also consumed, which answers my question.

Thank you again.
Dom

 

[jcolliii]

Coral skeletons (and spicules in softies, coralline algae) are aragonite (CaCO3) - need both calcium and carbonate ions for them to be able to mineralize.