I have had a recent bleaching of a few corals (started about 2 weeks ago) that I believe was spawned by letting my alk get low (got down to 7.5 or so and I normally keep 9-10). This happened because my calc reactor ran out of media and the levels dropped (I know if I were testing at the proper intervals I would have caught befor it dropped so low.) Over the last two weeks I have slowly brought alk back up, it is now back to 8.8. I am still having STN issues and it seems as though it is passing from coral to coral where corals are touching. It is happening slowly where a colony will take a week or so to totally belach. I am wondering if the sweepers from the plating coral in the pic (I've seen them, they are pretty long) are stinging my corals and stressing them into bleaching. I see what look like tell tale bite marks for AEFW in some of the corals near the plating coral but I am wondering if these may be sting marks? I have not added any corals to the tank in the last 9 months so I know nothing new has been introduced. Is it possible for AEFW to wipe out coral this fast, could they have been dorment in the tank then exploded when corals got stressed? Another possiblility is that the tissue from the dying coral is becoming dislodged then landing on helthy corals and causing them to STN (is that possible?) In the pic, the sections of dead skelton with algae on them have been dead the longest and seem to be convieneantly closest to the plating coral. Also you will note that the STN has spread from the Blue Tort to the Birdsnest at the upper right. I guess I need to get fragging on the birdsnest. Any help or ideas of what I should do would be greatly appreciated.
