My understanding is the carbon dosing will effectively deplete the Nitrate and leave the phosphate levels relatively unchanged because of Redfield's ratio (C:N

= 106:16:1). That's precisely why you need to run GFO which will preferentially bind the excess phosphorous that accumulates through bacterial consumption of the N via the C dosing. I'm no chemist, but that's what I gathered from the threads on the chemistry forum.
IMO, carbon and nitrate dosing to reduce phosphate levels would be a pretty ineffective means of reducing phosphate compared to running GFO in a reactor. IME, the carbon dosing helps maintain levels of Nitrate under 5ppm, and GFO and good maintenance to keep p under 0.06.
I could see the use of nitrate dosing where someone already has ultra low levels of phosphate, and doesn't want/need to run GFO, but wants to maintain low levels of p...unfortunately, that isn't the case for me :spin2: