Yea, there are 2 different ammonia test kits made by AP. The one I have is from 0(yellow) to 8(dark green). It goes 0, .25, .5, .75, 1, 2, 4, 8.(or something very similar)
Mine came with the freshwater testing kit.
I think it goes from white(0-.5) and different shades of very close yellow from 1-2, 2-3, 3-4, 4-5, 5-6 or something similar to that
I have the yellow to green one. If it is anything besides yellow I add a bit of prime or do a water change. It isn't a question of how green, just is it green. And err on the side of doing something, rather than nothing. I also play with the light source's placement in relationto the card to get the best color view.
mine is the clear to dark yellow kit. I don't find it any mre difficult to read tan any other kit I've used. hold it up to the white part of the card and match the shades.
Dave
I have the yellow to green one, and I agree with one of the previous posts - I look for yellow and if I see any hint of green, it means trouble somewhere. I always use natural sunlight outside to check the colors, as incandecents can make it hard to tell what color any of the tests are...especially strip tests.