I just got home from a weekend away and the bottom of my tank is brown as well. Not the whole thing, but it looks just like the pic above from squidward.. pH 8.2, Amm. 0, Nitrite 0, Nitrate 0. whites 11-7, blues 7- depends... No fish, only coral and my cuc. Only had it for about 3 months, but so far everything has gone just fine. Oh, and I cant seem to find any of my hermits or other cuc besides the turbos. Whats going on?? Thanks in advance