AMMONIA
Here is a couple of interesting articles, including an interesting calculator regarding ammonia. You may need to join PFK to use the calculator, but you may as well join, it's free, easy and lots of valuable information, calculators and product review etc.......
http://www.practicalfishkeeping.co.u...article_id=431
http://www.practicalfishkeeping.co.u...es/ammonia.php
Me, personally, i am stopping testing for ammonia now, as the water conditioner i use (Seachem Prime) creates some problems with testing for ammonia (false positive results). I am satisifed my biological filtration is processing ammonia as it should.
I did try a testing kit (Seachem) that provides true "free ammonia" results even if you use a conditioner that can provide false-positive results, but i didnt like the test kit, see below.
If you are not using a water conditioner that converts ammonia to a non-toxic form (such as Prime) your testing results for ammonia should be "ok" and reliable. Tetra Aqua Safe is a water conditioner that does not convert toxic ammonia for example.
Here come's my previous experience with ammonia testing kits and price information