What is the min/max I should be trying to maintain and if it exceeds the max, what methods are best for reducing it?
You calcium level should be anywhere betwwen 380-450.
Reef Aquarium Water Parameters by Randy Holmes-Farley - Reefkeeping.com
"It does not appear that boosting the calcium concentration above natural levels enhances calcification (i.e., skeletal growth) in most corals. Experiments on Stylophora pistillata, for example, show that low calcium levels limit calcification, but that levels above about 360 ppm
do not increase calcification."
The only way to really drop it is do water changes with a salt that has a lower calcium level than your system has.