Testing question..

[Bryan47]

I will preface this with the fact that I use API test kits, if you have other recommendations let me know, I'd love to get the Hannah checkers or something digital and less prone to human error.
So I am doing my weekly full test of every parameter and my nitrates were rather high so I knew a water change was in order so I pulled up an online calculator for lowering nitrates. The first required input is nitrate level of tap water. I never considered my tap water would have nitrates so I tested it. It read 20 ppm. I think the EPA allows 10ppm maximum. I of course use prime so I would imagine that takes it down gradually.

My question is about when I read the test. I have always held it to the white background however this drastically darkens the color. Without a background it's between 5-10ppm. So do you hold it to a white background or no? I have posted pictures below of the effect I'm sure many of you are aware of.

 

[saltyphish]

Hold it to the white background as the directions state. When in doubt follow Manufacturers directions. Also even the Hannah checkers are prone to human error. I only recommend the phosphate, and alk tester from them. I don't care for the api nitrates test kit myself. I found them to be inaccurate for me. I use a salifert nitrate test kit.

 

[Bryan47]

Thanks I'll give that a shot!