Is your problem with ALK being low or being not stable? Low ALK can be raised with baking soda or any ALK buffer in a bottle. If you're having swing in your ALK, you'll either run a calcium reactor or a dosing pump
I do wonder about mg, looks like his ca is high and all low. If there isn't any imbalanced dosing driving that, then it looks lika a classic case of low mg.
i agree with this is me. if you just have low alk, you can slowly raise it. if it swings too much, then dosing pump is the way to go. bulk reef supply has some good videos about maintaining alk, mg, and calcium.
If those zero nitrate and phos. readings are correct, 7 dkh is a good alk value. What did you dose your tank with that caused alk to drop and ca to rise?