Accuracy of expired test kit?

[tang daddy]

Well buddy all I can say is if you're dosing calcium in your tank and your sps is not massive colonies then the test kit may be wrong....

My ca never dropped that low even without dosing for a few months although I didn't have much sps at the time.

If your sps is STN it could be alk too low or unstable and fluctuating or predation.

If your alk is high the tips usually burn from my experience.

Good luck man, hope you figure it out. Also you can raise ca 100ppm per day safely.