That's high, but fine. It will precipitate out if it is too high, but I do think corals get irritated if it is well above 500 and more than anything it will change magnesium levels and alk consumption. That is really why you want certain numbers, any of the three elevate and it is like scales balancing and can either tax another element or cause it to not be able to be consumed properly.My reef crystals always mixes up high on calcium. 470-490 still okay? I don’t think I’ve ever seen it below about 470.