I used to do a 10% WC every 1 month or 2. For some reason, recently I have to change 10% (2nd one the next day) twice one day ever 2 week. If I don't change, my red plating monti will start bleaching! (Nitrates and phos not even that high prior to WC (5 and 0.25, respectively). I guessed my corals are spoiled.