Low Calcium

[gregzz4]

I'll agree with 2 points

Check your kit against someone elses and if that doesn't help, try double-dosing your tank for a day to see what happens

Because your Alk is so high, I'd think you're going to have issues bringing you Cal up

And because your Mag is lowish, it may cause issues too

I'm not saying 1300 Mag is low, but your params are out of balance, so it'll take you time to get things together

If you keep having issues bringing your Ca up with your higher Alk, I'd recommend you boost your Mag
Then you may have an easier time balancing your Ca and Alk