Have you verified your calcium readings with another test kit? Sounds like your test kit is off. Most salt water mixes will not have a calcium reading of 500 right out of the bag, most are closer to 420 if that. To answer your question though, yes too much calcium can cause your water to be cloudy. The reason it appears cloudy is that the water can no longer hold any more calcium and so some precipitates out of solution. The only way to fix this is to lower your calcium. A lot of times you will see this happen if you have a calcium reactor either pumping too much CO2, or with too high of a drip rate. I would double check your measurements and go from there.