ICP vs home testing discrepancies

[X-37B]

Was just reading this as I was on another thread that posted results from ATI which is who I use.
Their values are/were way off from my previous 2 tests.
Not sure why but it's concerning as I use them.
Look at their ideal #.
My test then the one in question

 

[Randy Holmes-Farley Verified Community Expert]

Was just reading this as I was on another thread that posted results from ATI which is who I use.
Their values are/were way off from my previous 2 tests.
Not sure why but it's concerning as I use them.
Look at their ideal #.
My test then the one in question

To clarify, what are these two tests exactly? The first is now, both now???

 

[X-37B]

To clarify, what are these two tests exactly? The first is now, both now???

The first is mine the second is from another thread who just had one done.
So different systems.
I question the ideal values as both came from ATI.
Many ideal values are different from the same company.
Ca 300 ideal?
K 490 ideal?
Somethings way off on their end.

 

[Randy Holmes-Farley Verified Community Expert]

Ideal values from ATI are based on salinity, and will change.

 

[JonasRoman]

One more reason besides that No3 can have been consumed, its that you have high nitrit, making your own NO3 values false high. You said you did with a Hanna checker HR? They are pretty good, but if nitrit is very high, it will affect. Last week I helped a guy that Hanna checker HR gave 15 mg/l NO3. With other methods the tanks was more in 5 mg/l area. Then we tested nitrit that was 1 mg/l in this tank. Such high nitrit affects nitrate values from hanna checker HR with false high of 10 mg/l. So if you have nitrit below 0.1, (gives false high NO3 in Hanna HR by 1 mg/l), I would say it's not that as a reason. So test nitrit, then you know if you can exclude that as a reason.