I had a 55g with 260w p.c.'s and had anemones and thought they were fine.
However, I upgraded to a 110g and added 240w of t-5 lighting and WOW.
Now granted I only have a condy but it has flourished. I did have a beautiful lta but it decided to wonder into the p.h. (if anyone know of a sponge cover over a koralia type p.h. let me know).
I would say that not only is tank size important but also how deep is yours. My 110g is only 18" (the same depth as a 55g, I think). Thus, if I'm right the light will be more effective than if it was on a deeper aquarium.