Nitrate levels

[realnew]

I tested my params the other day, all were good except Nitrate. It was off the chart. I was using the Saltwater Master Test Kit. I went to a reputable LFS and purchased a new Nitrate test kit from Red Sea. When I test with this kit, I receive results of approx. 5ppm. The advised I purchase some Nitrate Sponge and put it into the sump of my wet/dry. They were more than a little shocked at the difference between the two tests and even tested a sample of my own water at the store with the same results.
Does anyone have an idea about why there would be a difference between the tests, and which one should I rely on. I haven't had any deaths, and I am sure that if my Nitrate levels were at 200ppm things would be going south in a hurry.

 

[birdy]

The saltwater Master kit, is about the worst test kit out there IMO. Red sea is a little better but I don't really like them either, but I would believe the red sea test.
Salifert are the most accurate tests I have used.

 

[realnew]

Thanks, I think I am going to try to find the Salifert test today. I just can't figure out the difference between the two results. We are talking a difference of almost 200 ppm