Very high Calcium - Where should Alk be?

[Randy Holmes-Farley Verified Community Expert]

That's interesting because I have read that calcium and KH are inversely related. The higher the calcium, the lower the KH. I have also heard that temperature plays a factor with this as calcium breaks down at lower temps but does not break down as well at higher temps. Does this sound correct or am I not understanding?

Calcium tends to combine with carbonate to form insoluble calcium carbonate. The higher the concentration of the two gets, the more likely this is to happen, so when both are high it is most likely and when both are low it is least likely. Higher temperature makes it more likely to happen.

If you were adding calcium and not alkalinity (carbonate), the precipitation would tend to reduce alkalinity as the calcium stayed steady or rose, and the same can also be true in reverse.

But that says nothing about what levels are desirable for organisms or reef tanks, only what reactions take place under what conditions. So, for example, a coral does not prefer lower alkalinity just because calcium is high and it does not prefer lower calcium just because alkalinity in high.

I hope that makes sense, but if not, I can explain further.

 

[Surfandturf]

Calcium tends to combine with carbonate to form insoluble calcium carbonate. The higher the concentration of the two gets, the more likely this is to happen, so when both are high it is most likely and when both are low it is least likely. Higher temperature makes it more likely to happen.

If you were adding calcium and not alkalinity (carbonate), the precipitation would tend to reduce alkalinity as the calcium stayed steady or rose, and the same can also be true in reverse.

But that says nothing about what levels are desirable for organisms or reef tanks, only what reactions take place under what conditions. So, for example, a coral does not prefer lower alkalinity just because calcium is high and it does not prefer lower calcium just because alkalinity in high.

I hope that makes sense, but if not, I can explain further.

It's interesting that's for sure. I know that in the nano I have now I had an unusually high calc reading of 580 or so ppm and a drop in my of about .025. This was noted in my weekly water test. It was a huge change from calc being at 420ppm.