justethe, if ur talking about the colour changes when u test ur water for ammonia, nitrites, nitrates, ph, gh, kh, etc., isn't there a guide on the back of ur pack telling u what colour means what? i think it depends what indicator dye is included in ur pack as to what colour "normal" or "safe" is. if there's no guide on the pack, ask ur lfs.
or if i was completely off the mark in what u were asking i'm sorry, blame it on sleep deprivation!!