Nope, just looking at the dynamics of the Calcium supersaturation quotient, with alk and the Ca++ at the posted level, the solution would have precipitated Calcium Carbonate unless there were some unusual circumstances for a reef tank. This makes the test kits suspect, although I really do not know the kit listed.
It is difficult to get calcium much above 450 under most reef aquaria circumstances, ESPECIALLY with alk much above 6 dKh or so. To do this, alk has to be somewhat depleted, pH has to be low, and salinity has to be dead on and be of perfect conservative element ratios. If the alk/buffer was high, it is difficult to get the pH low enough to maintain Ca levels above 450 to 500 (unless you're bubbling CO2 into the water or dripping vinegar). Test results above 500 under normal reef aquaria conditions and salinities, temps, and conservative proportionalities usually indicate either method error in testing or faulty or inaccurate test kits. Effluents from Ca reactors will have 600 to 800 PPM levels without precipitation, but this is due to their low pH (6.7 or so.)
Additives may have extremely high levels, as will tanks that have just had additives or boosters added, but for the most part, high Ca and alk in normal reef aquaria conditions result in abiotic precipitation or sudden triggered "snow " events to reestablish equilibrium based on saturation quotient predictions.
Short answer? test kit error or methodology error.
...just late light mental rambling, I cannot sleep tonight,an unusual situation for me, although I do stay up late often.
