How long has your tank been cycled?
Zoas, at least the common ones, are pretty tough, they'll probably be okay as long as your tank is stable. Just don't start adding any more demanding/sensitive corals until your tank has been stable for a while, or you risk killing the coral and losing your money.
Calcium you want to maintain up around 400-450, phosphate needs to be pretty much 0ppm. You also need to keep an eye on your kH
and Magnesium levels if you opt to get into more demanding corals, such as SPS