Chrispixx
Fish Crazy
I have never seen a nitrIte test do anything but pale blue for negative and dark purple for positive. but thats just me... if rdd says it can turn green, clear, brown, red, yellow. then it must be true. I've only seen pale blue/purple.That is definitely an indication that it is very high. API kits will eventually turn to green and then clear when the level is super high.
Personally what i would do is crank the ammonia back up to 5-6 ppm and test ammonia and nitrIte every two to three hours. That way if it is processing nitrIte you will not miss it and you will see the test go from dark purple then get lighter over time. If this color change doesn't happen and you still get the same weird nitrIte readings that you are getting now then you know its not processing nitrIte and it is more than likely off the chart (very high) (unreadably high).