lighting advice

That would be bare minimum for keeping even low light corals. You want 4-6 watts per gallon for most corals, and the depth of the tank is important. With a 55. you'll need strong lights to penetrate very far. You could keep a few corals with those, but they would be surviving, not thriving, IMO.
 
for a tank less than 24" (probably your's, how deep is your's anyway?) you should have about 300 W (for 5.5 WPG) and you should be all-set for the corals you want to keep.

BTW I have a mini-reef (20g) and I have a PC (65W) and a flourescent (15W) so I got 4 WPG on a 15" deep tank. I have a xenia,
striped mushroom, starburst polyp. I wanted a flowerpot but found out that it's an LPS (guy at LFS said it would be fine under medium lighting and water-flow, I don't know), would it still do fine? If not, I could bump it up to 2 PC's and 6.5 WPG that would be perfect, right?
(just checking)
 
Just came across this. Please avoid the flowerpot. They are constantly being imported, despite the fact that most of them die in the first year. Until their requirements are better understood, they should not be purchased.
 
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