One of the issues with light source was that a fairly high number of the CFLs (compact fluorescent lights) (any fluorescent for that matter) can have this characteristic of adding a greenish tint to things that are in the clear-yellow type range. Fluorescent technology just has a wider range of shades that are being put out as products. Incandescents too can vary in color output, as we all know.
All of this is swamped by the huge variation in individual human interpretation and communication though, I think. One person's darker yellow is another person's light yellow. One person's paranoia about a slight hint of green is another person's "too insignificant to worry about it." In my experience, the API ammonia tests that I've used have indeed displayed a very clear, very light yellow (very pale and refreshing looking, as opposed to thick, if that makes sense) once the filter is mature and doing its best job.
I have also run tests with before/after dechloramination (my water authority uses chloramines 11 months of the year and I get email announcements from them for the one month when they flush with straight chlorine.) The dechloramination clearly separates off some ammonia and it becomes detectable after the conditioner is used. Its trace, not up at the 0.25ppm level in my experience.
Separate from the chloramine thing, its very, very common to have some trace ammonia (just like nitrates) in tap water, so this is an added complication. For fishless cycling one thing we should try to look at in threads is what the whole history of the fishless cycle effort is like. I think we should try to avoid letting the paranoid people get stuck going on and on with a tiny trace left at 12 hours. Instead we should just cut it off when we see that and have them switch over to watching for whether they have a fish-in cycling situation after their first stocking. This is for people that have had a clear, long cycling process that appears fairly normal. For cases where things seem to rush to conclusion in 3 or 4 weeks we should be much more cautious, as there may still be significant nitrite spikes left to come if they were to jump to their initial stocking.
~~waterdrop~~