I've got more experience with blastos than acans. With blastomussa wellsi I keep them in low light and low to moderate flow. I feed them weekly (at least) with a mixture of mysis, cyclopeeze, oyster eggs and selcon. My merlettis, wellsis and acan lords all readily devour the mix. As far as wellsi growth, they do not seem to grow well for me. In similar conditions I've had one small colony grow slowly while the other has slowly lost polyps (started with about 9, down to about 4 over the course of two years or so). I've read that as they are generally collected in deeper water they like lower temps (mid 70's) lower light (I keep mine under an overhang... way under an overhang) and lower flow (enough to keep sediment off of them but not so much as to cause the polyps to close). I've read way too many stories over on RC about blastos fading away. In the future I won't acquire any more wellsi. Just not worth it IMO.
On the other hand, IME acans are quite hardy. They are more tolerable of different lighting and flow. I keep them under both T5s and halides and they seem quite adaptable under either one. Acclimation to higher light should be done slowly though. I feed them at night when the tentacles are out (in fact one of my frags has extended tentacles almost all day long and is definitely the fastest growing of my frags). They get fed at least twice a week if not three or four times.
Garrett.