Nitr-ITES are bad, Nitr-ATES are good (unless they are in the stupid high numbers). Ammonia and Nitrites should not be present at all after the cycling phase is over, the bacteria should be able to keep up. Salinity swings of .02 in 24 hours usually aren't deadly BUT in the case of urchins who are ultra sensitive to those kinds of swings, it can be. They are very similar to starfish in that they don't tolerate parameter changes well at all and small changes can kill them.