I use Fermax which contains:
diammonium phosphate, dipotassium phosphate, magnesium sulfate, autolyzed yeast.
According to what I have found, LD Carlson contains:
food-grade urea and diammonium phosphate
While I am sure the Carlson product will not hurt anything, I believe the Fermax would be the more complete choice. But I have never used anything but Fermax.