Both Arginine and Ornithine clear Ammonia but Arginine is twice as efficient in it yet cannot be used at bed time or with covert herpes.
I did read or hear this somewhere I don’t have a reference for it but if I had to bet I would say HC, either in the new book or an audio I listened too.
Removing ammonia is a non issue if you use a zapper anyhow, anything that hatches overnight can be zapped or treated in the daytime. Heck with the T2 you can take your Ornithine and turn on the T2 while sleeping if you are really paranoid :)