Sebae Died - Poison'd The Tank!!!

+1 for carbon. i feel for you, the exact same thing happened to me. i made the same Sebae mistake as a newbie. i lost a clownfish (i had a mated pair), 3 sea cucumbers and my entire CUC. i changed about 90% of the water and ran carbon (chemi-pure). my tank went into a mini-cycle and i had a diatom algae bloom but after that everything was fine again.
your tank isn't mature enough for an anemone especially not a Sebae one.
just out of curiosity, how long did you have it before it died and what color was it?

 

The Sebae mistake? Are they known for this?

I had it for about two and half weeks and it was doing fine, my two Tomato clowns loved it. It was an off white type of color.

I'll get some granular carbon tomorrow, and change more water this weekend. Such a let down that this happened, the tank was doing so great!

 

Anemones in general are known to have horrible survival rates. Sebae nems have an even lower rate than BTA and Condys.