No problem!
When I first got some subwassertang, it fragmented into dozens of pieces. The fragments eventually grew into decent size pieces. IME it does not require a lot of light. I have some in a high tech setup with med-high light, ferts, and CO2 and some in a low tech, no CO2/ferts. Both are growing well.
One thing I have heard (but have not tested) is that it is sensitive to Excel or Glutaraldehyde. Since it is an algae, I suppose H2O2 might not be a good idea.
I do have a few fragments growing in a terrarium. They produce numerous hair like roots on the underside of the "leaves". I believe high humidity is key to keeping it from drying out.
Sent from my iPhone using Aquarium Advice