Rons, lighting explanation is helpful but I also agree w. Topshelf, really varries among species of nem and BTA's are more forgiving in this area, expect it will probably climb up high w/ that light fixture you have now.
Your easiest resolve IMO is to add something like a 2 lamp T5 strip to what you have, and really my own preference is to have a T5/LED combo.
As or more importantly hopefully your tank has enough established LR to be stable enough since it's new, normally we wait at least 6mo for a nem.