I am stupid, Calcium way to high. Please help

[Hail_Ceasar]

I have recently been having troubles with my 29g biocube. It has been up for over a year now and i have never had anu deaths till this month. then in a week span both my cleaner shrimp, my clowfish, and my yellow tailed damsel all die. Cyno wreacked havoc on my tanks and a few of my corals are a shadow of there former selves. I feared my tank was crashing but after checking my water i discovered nothing was high but phosphates and they were still at acceptable levels.

However i have not checked my calcium in a long time, i had a routine calcium adding time and i never really checked for a while. Well I went out and bought a calcium test kit (lost the old one) and checked and my calcium was at

840 ppm!!!!!!!

Is this the reason my tank has been having problems and what do i do to safley drop the levels. Also I have been having a hard time keeping my ph over 8

Lesson learned alway test.