ICP nitrates vs Test kits

[Kruss7]

I just did a Fauna Marin total ICP, results for what I’m inquiring about is pictured.

When I do my hanna test kit my nitrate comes between 25-30 depending on the day I do it. I did it the day I sent my ICP and it came back 26 and today 28.

The ICP measures 5.5. What should I be trusting? Is the ICP accurate for nitrate?

Going to do a third test this evening with a salifert test kit.

I also clean the cuvettes very well with RODI. I flush the cuvettes with tank water as well.

 

[Science/G]

My Hannah checker was spot on with my ICP test fwiw

 

[Kruss7]

My Hannah checker was spot on with my ICP test fwiw

Interesting with mine being so far off… wonder if it’s the test kit or the icp…

What brand icp?

 

[Acrononomus]

Did u happen to feed before the test was taken ?

 

[Kruss7]

Did u happen to feed before the test was taken ?

Nope plus the handheld is consistent at that range.

 

[Science/G]

I did an ATI. Is your reagent very old? Is the vile clean? Did you have an accurate 10 mL measurement? Did you shake the bottle for the full 2 minutes? Obviously all of these things can impact the test but that's a huge difference between the two tests.

 

[Science/G]

Looking back maybe spot on wasn't the best term to use. I tested 18 ppm it came back 22 ppm. The sample was taken 3 days later.

 

[areefer01]

Looking back maybe spot on wasn't the best term to use. I tested 18 ppm it came back 22 ppm. The sample was taken 3 days later.

A lot can happen in 3 days. On a hobbyist level, not professional as they have other standards and gear, just collect a couple cups of water and do everything with it. This way at least you have the same water which will rule out 3 days of unknown.

Example below of a recent run I did.