So I should something to boost calcium and that would fix the corals or do I need something else as well...?If correct, calcium range is 400-440
Increasing calcium will change Alk reading. Do the calcium increase first. Calcium and alkalinity levels are interdependent. The basic rule of thumb is when one goes up, the other goes down. For example, when the alkalinity level is high, the calcium level will likely drop significantly in the water which is likely happening in your tank