True alk reading

[Tava176]

I know that if one tests PH just after the lights come on in hte morning, it will test a little lower thatn if tested after lights have been on for....lets say 4 or 5 hours. Does this hold true with ALK testing?

My lights fust came on and I tested water.

CA 440
ALK 2.98.

Balanced ALK for a CA of 440 should be around 3.94.

Should I wait and test ALK after lights have been on for awhile or will that not make a difference?

 

[Randy Holmes-Farley]

No, alkalinity does not vary day to night. It steadily declines except when one adds alkalinity.

FWIW, I would not worry about the "balanced" alkalinity. I'd target 2.5-4 meq/L,regardless of the calcium level.