I have never looked at plant fertilizer, tbh i would have to look into it before i could really comment, but i suspect i wont like what i see
2 grammes is a lot, i mixed sodium nitrate @ 85g/l and dosed varying amounts but generally 10-30ml every 5 days in my atu (so its a near constant slow dose)
Currently my po4 is just creeping up a little as i have knocked the skimmer right back (0.024) so i am contemplating introducing a little nitrate to bring po4 down slow
Its my experience that the lower po4 is, the more nitrate you can get away with putting in, without being able to test a noticeable change by way of nitrate increase, or po4 reduction
For me at least from the perspective of having large akounts of filtration, its pointless attempting to use potassium/calcium/sodium nitrate to inxrease no3, as its processed so quickly, i onky use as an occasional means to control po4 instead of using gfo (havent used gfo now for 2.5 years)
Hth mate