I've use SeaChem and Kent etc, I find little differences in brands.
I am in the school of thought that feeding the tank well to supply ALL the N and P is a good move for perhaps 95% of all Marine plant tank set ups.
I am going to start measuring uptake rates for NO3 and PO4 in the plant tank I have.
I am playing around with variations in dosing of Iron and KNO3.
Regards,
Tom Barr