I'm about as far as you can get from an expert on this subject, but I remember seeing another thread about something like this before. One guy had posted about how back in the day they used to use 40 & 80 watt bulbs with anemones. He said they grew, split, and grew some more without any problems.
From what I've picked up in various threads on this subject and from talking with some experienced people, the general consensus is this: BTAs are one of the lower light requirement anemones. They will survive under PC lighting in a "typical" standard depth tank and will be able to thrive if: water conditions are good and stable, and if you are feeding them properly. An anemone with lower lighting will have a higher food requirement than if you had high intensity lighting.
Again, I'm new myself, but I have read MANY threads like this. I erred on the side of caution, so I'm running 250w MH on a 90 gallon for my RBTA & GBTA. This also gives you the option of growing any coral you want. However, this would be kind of irrelevant in your case considering you are putting it in the sump.