API Stress Coat interfering with API nitrate test

[andy01748]

I have just confirmed that API's Stress Coat interferes with API's nitrate test, causing a low or false negative reading in the test. I am wondering if the chemicals in API's Stress Coat are actually removing the nitrates (doubtful) or interfering with the test (I assume most probable). Is there another nitrate test that uses a different chemistry whose accuracy won't be affected by the Stress Coat? If people use Stress Coat they should be aware it may cause an issue with the API nitrate test.

 

[bertoni]

It's interference, although I don't know what kits might work in combination with that product.

 

[tuawcxs]

Dosn't Stress coat remove chlorine from water. Since your using RODI do you really have to use stresscoat or are you using it as a precaution? Is this just a test your doing?

 

[andy01748]

Dosn't Stress coat remove chlorine from water. Since your using RODI do you really have to use stresscoat or are you using it as a precaution? Is this just a test your doing?

I noticed the issue when I was troubleshooting my skimmer. I looked for a aquarium safe product that I knew would cause the skimmer to foam. Adding a couple of drops Stress Coat directly into the skimmer foam head did indeed cause additional foaming, but when I tested the skimmate for nitrates it was 0in an aquarium that is 20 ppm. I confirmed the problem by testing water from a tank I have curing rock which has nitrates present at >100 ppm. When I add a drop of Stress Coat to the vial before doing the test, I get a 0 reading.