API ammonia test tube clean as a new one!

I'm not sure if this will be useful to anyone else and to be honest I'm not exactly sure at which stage it happened, but I was pleasantly surprised by this.
So in my API saltwater master test kit, I always end up using the same tube for ammonia test. I can do this because no matter how much I rinse it or how many paper towels I try and stuff down it to clean it, there always seems to be a white scale like build up inside. All of the others are always as clean as new.
The other week I was panicking about something and tested my ammonia and nitrates to start trouble shooting. Both came back with their normally low result and I think I eventually decided I was imagining things.
The tests were sat down next to the tank still full and I kind of just left them there.
Finally got motivated enough to rinse them out tonight and after tipping out the ammo test, I tipped the bright yellow nitrate test result into the unrinsed ammo tube. It quickly turned to a dark red and kind of bubbled a little bit. After giggling at the reaction for a little while and waiting to see how dark the color would get, I finished rinsing them in tap water. i'll note that the tube didnt seem to heat up and this seemed safe enough to do, but I'm not about to recommend using these test results to wash your hands or anything.
When they were done and dried, the ammonia tube was as clear as a brand new one!
I'm not sure if anyone else gets the same build up, but I've noticed it on 2 of these kits now, and being as picky as I am, that buildup has always bothered me.
Now that its gone I thought I should share my experience incase anyone else wanted to try it.

 

awesome! i have the same test kit and i have a terrible habit of leaving the tests sit in the tubes also. but this made me wonder. one time i tested for nitrates and got a bright red and i freaked. i quickly rinsed out the tube and tested again and got yellow...maybe i had not rinsed out the tube well enough and it still have some of the ammo test in it? i dont normally pay attention to what tubes i test with what but i was owndering for a while why i went from red to yellow with in a couple min (i figured i didnt shake the bottle long enough haha). thanks for finally solving that for me haha!

 

Always rinse the tubes right away after testing.This will help keep the residue from forming.;D

 

I will try to from now on...i get lazy sometimes haha, also your avatar makes me laugh everytime i see it...gotta love Dr. Evil!

 

I used to rinse them all the time after testing and still always had problems with the ammonia tube, all the others were fine.
Maybe theres just something wrong with my water lol.

 

No there is nothing wrong with your water its just the reagents in this particular test leaving the residue. Try some vinegar it should remove it.