Why my tentacle anemone has been died?

the lighting should be a min of a 50/50 bulb. anemone will NOT tolerate poor water conditions the few perimeters you've given are very high. do 20% water changes WEEKLY add calcium and other trace Elements as well as food for corals. they also like smaller rocks near them for to attached their foot to. do not handle them often if at all. spot feed them weekly with brine shrimp suck into turkey baster and gently squirt towards anemone. good luck