I have been having an issue with STN on a few of my sps. All parameters are within normal limits except for potassium which is at 330 per a salifert test kit. The Stn starts from the base and goes up from there. I also found a orange colored nudi and thought maybe it tried to dine on some of the effected corals. I am at a loss for what is triggering this. I have also thought that maybe my hermits might also be the trigger. Just would like to see what others think. The tank is a 60 cube lit by a 250 phoenix, 1 blue plus, and 1 purple plus. All the other normal stuff, skimmer, kalk, 2 part, gfo and carbon when needed.