Tanks a year old, and up until today at 2 PM the water levels were good. I have a clown, a small Huma Huma and a small Yellow tang. I know I know, way over loaded, thanks to my LFS......anyhow, I know thats oart of my problem, but why the major spike? I have 3 Mexican Grazers, 5 turbos and 10 blue legs. I scoop out the food they don't eat when I feed them and I have my dialy/weekly/monthy maintenance tasks. I just don't get it.. As far as do I run carbon. Yes, always have but never had this problem before.