feeding corals and nitrate

[mushroom samba]

does feeding coral brine shrimp and plankton and such produce nitrates?

 

[Amphiprion]

If it is allowed to decay, then sure. Anything that contains protein will ultimately break down into nitrates. Significant amounts of phosphate will also be found in animal cells. As for how much it will create if you feed brine shrimp, that will all depend upon how much you feed and how much is actually eaten (or whether it is rinsed, etc.).