ScotJudd
Aquarium Advice Addict
soooo I am getting 40ppm from my tap water? ??
I'm gonna test it again. That picture was 9 min after I stopped shaking it for the 1 minute.
I think you should read your API nitrate instructions carefully. They are very specific - I won't quote it, but any readings after the 5 minutes is up are not valid. The colour will continue to develop and you will get a false high reading. Failure to shake bottle No2 for 30 secs prior to test will give a false low reading. Nitrate is probably the most exacting water test to get right.