API vs. Seachem Nitrate tests completely different results?

[Chrissy]

I have been using API test kits for nitrates and lately no matter what I do, I get either 20 or 40ppm. Today, I used the Seachem nitrate test kit and that one reads 2ppm. Even my little 5 gallon that I just have snails and a crab in read 80ppm with the API kit, and reads 10 with the Seachem kit. Which one do I believe? That's a pretty drastic difference. Has anyone else experienced this?

 

[mrclam]

You could always try getting a third test kit as another point of reference. I have heard good reviews for salifert nitrate test, particularly for low range values

 

[tjbell]

I'm very interested to hear the results I would also recommend using a third kitI use an API test kit also and I think it reads high on nitrates

 

[Chrissy]

I borrowed an Elos kit from CaptainHook and it read 25 which is the highest that test goes. So Seachem nitrate tests don't work at all and a waste of money, apparently.
Here are my results in pics...

Before a 20 gallon water change:


And After a 20 gallon water change: