Any pics of your tank? I guess 55G is either 18 or 20" tall? It is not shallow tank, IMO..
Problem with 55 G is that tank does not have depth from front to back to aquascape to top with rocks (2/3 of tank height).
You can simply change to Glass canopy or leave it opened (fish can jump though, especially anthias) OR
Changed the light bulb to 50/50 by Coralife.
You can have corals that are not photosynthetic such as carnation, Certain Gorgonian/whip, tubastrea along with certain
LPS and softies toward top.
I still would recommend at least 80W of lighting for 55 G even with low light requiring softies and lps.
Why do it unless really prepared? I dont see a point spending money on lighting twice!