I have an Acropora colony that is showing signs of STN from the base up. I have heard this is due primarily to either a lack of flow around the base, and/or lack of alkalinity. I am sure it is not my alkalinity, as everything else is doing awesome in my tank. I suppose it is probably a lack of water flow around the base, however I did have an Acropora piece there before, and it did pretty well until I got rid of it. So, my question is ... if the tissue recession is due to a lack of flow, will the tissue recession continue up the colony until the entire colony is dead? Or will only the base lose tissue?