NEED HELP STAT!

My corals are not looking good... I tested the water and everything is ok except the nitrates are a little high, although I don't feel like this is the reason why. I've had them high before but it didn't affect anything. Recently I had an anenome die but I took it out right away, this was not even a week ago. I don't over feed and I just did a 20% water change. The tank is a 40 gallon with 10 gallon fuge. My soft corals were the first to show signs that something was wrong and now my long tentacle ...

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