Carpet anemone's require T-5 or MH lighting and they are really picky with water quality. They need proper PH, salinity, etc. However, they aren't that hard to keep. I gave my father inlaw a mated pair of percs and a carpet anem for his 50 gallon. It stays in the left hand quarter of his tank.

Like any other anemone they do sting other corals and it will limit you on corals. They tend to move as well. I have a very large 18" diameter pink bubbletip in my 95 gallon. He will sting any coral in his area, but he is awesome to look at. Hence I now have a 24 gallon for my nicer corals. The zoanthids seem to be immune to the sting, but they will close up and starve if the bubble tip stays over them for a long period of time.

It depends on what you want for your tank. They are awesome animals, but do cause issues with other corals. They will also eat any fish if caught besides clowns. I haven't lost any corals or fish, but it sure pissed me off a few times. Having to move my corals around so he'd stop stinging them. You will have to mess with your powerheads to move him into a different area. Anyways, they are great additions, but be cautious especially in a 55 gallon tank. They get rather large.