Benn doing a little research on this one, just for you guys and me (Johnny No 5 need more data. lol) and it seem I am wrong!!!
I've linked to the thread for your interests but be prepared for a thorough read and have Wiki open next to you to search for any terminology you don't understand (I have. lol)
Happy reading guys and one more item in the data bank for me
http

/ukaps.org/forum/viewtopic.php?f=11&t=925&hilit=urea&start=10[/qipte
For anyone not able to se the link then Tropica uses ammonium nitrate AND although most other use Urea it seem it quickly breaks down to ammonia (or maybe ammonium).
However it should be noted that ammonium is not ammonia. Much much les toxic so I am now assuming that the ammonia test kits pick up ammonium too.
AC