Low Alk in freshly mixed Reef Crystals Orange Box?


New member

I am finishing up an orange box of Reef Crystals (couple years old). I just noticed the alkalinity in the mixed salt is only 7.5 dKH (my tank is around 6.5 dKH). I checked this with a Hanna Checker, and Salifert Test kit. Both confirm 7.5 dKH in freshly mixed salt (mixed 4 gallon bucket with salinity as 1.03 because my 80 gallon tank is 1.024 and I am trying to raise the tank salinity to 1.026). Before mixing the salt in water overnight, I also mixed the dry salt bag (half used).

I should note, the salt was clumped together rock solid and needed to be broken apart and mixed. It's as if moisture got in the bag. Could humidity have reduced the alkalinity? Does the salt have a shelf life? I'm very confused because I thought my alkalinity would be 11-13dKH. I read Reef Crystals has some of the highest Alk. I just purchased a new box of Fritz RPM High Alk (red box) and will mix that tomorrow and see what I get. Any idea what went wrong with my older bag of Reef Crystals?

Should I throw this remaining bag of Reef Crystals away, or keep it incase I ever need to reduce Alkalinity?

Thank you