Question.....I have been testing my ammonia, nitrites, and nitrates for some time now using the API Master test kit. I have recently noticed that I take my reading at the 5 minute mark like the user manual states. However if you wait a little longer (few minutes) the color in the tubes keep changing. So is the accurate reading the 5 minute mark or when the color stops changing? Has anyone else noticed this issue?
What colors are changing? A zero nitrite reading will still look zero even days later (aqua blue color). A zero ammonia reading may take on an orange hue with time (such as overnight or days). Ph shades should not change and should be read immediately. A zero nitrate reading will still look zero days later and other shades tend to stay the same in my experience.
The most accurate results generally are taken at the proper times but if your doing a fishless cycle and dosing ammonia, excess nitrite can cause inaccurate readings (such as a purple shade turning blue or another color after 5min).
Sorry should have explained better, an example my ammonia would show a 1.0 ppm at 5 minutes but around 10 minutes it would show .50ppm, same for the nitrites, but my nitrates would go up in value and it is a fishless cycle
Yeah, usually it the ammonia, and nitrates wont change much after five minutes... ive left them in the tubes over night, and all ive noticed was the pH ones get a little off colored and the ammonia turns a very pale orange.
Just remember for nitrates, you need to shake the second bottle for 30 seconds. Add drops from first bottle, then shake the tube. Then add the drops from second tube, and shake the HELL out of it for a minute. Like as hard as you can. If not you will not get an accurate reading.