Needing some advice for my Heteractis magnifica!

[Joslyn]

I've had a heteractis magnifica for about 18 months now.

For the first 6-9 months it didn't look very healthy. The tentacles weren't full and it had a habit of walking around for the first couple months.
At that time nitrates were around 10ppm, and for lighting I had 4 X 55W T5 bulbs over it. (6 foot 180 gallon tank).

Then I put in 250W 12k metal halides. This made a big difference, but I'm not sure if it was directly as a result of the lighting change, or because the lighting grew algae in my tank, which removed the nitrate so that now my nitrate level is undetectable.

Is it eating? It's a good sign if it responds quickly to food and is sticky (stinging the food).