If you have a tank with fish in it, you would have to be very careful with dosing ammonium sulfate/nitrate/chloride or whatever else there is available. The fish don't like the ammonia/ammonium at all! I have read that it can be done, just very carefully! I just put up a thread asking for advice on this topic. I just got ammonium nitrate and I am having a hard time finding out how to dose it correctly. Rotala butterfly's ammonium nitrate isn't working and it is getting me frustrated.
As far as the algae thing goes, the only stuff I could find out about that was the same as above, if done correctly, it doesn't cause algae. This info is all from one single thread on this website: https://www.plantedtank.net/forums/...rameters/1288753-nh4no3-ammonium-nitrate.html
This is the only info I have been able to find on it, myself. Maybe others out there that have more experience with it can chime in?
To answer the original question of what is it that is being dosed, it is generally Urea, Ammonium Nitrate and Ammonium Sulfate. There may be others, but, I am not aware of them. Urea is the most popular as far as I am aware. Sorry for all the edits...