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Using the Mardel strips, the reading is clearly 35-40ppm (closer to 40ppm). Using the Aquarium Pharmaceuticals kit, I get 15ppm, 20ppm at the most.
Why such varying results? I even had my wife look at the results and she agreed with what I mentioned above.
These test kits are driving me nuts. They're so inconsistent. Even with the Ammonia kit. Using Mardel, it is clearly 0ppm. With the AP kit it's closer to .01 or 0.2 ppm.
I didn't go look up your test kits but this is often a problem that many forget and I see it here again maybe. First, does it say that both kits can be used in seawater Check your kits for the below units of measurements.
There are 2 different units for measuring Nitrate, Nitrite and Ammonia in seawater and freshwater
NO3-N & NO3 = Nitrate
NO2-N & NO2 = Nitrite
NH3-N & NH3 = Ammonia
Lets start with the first one. NO3-N = **Nitrate Nitrogen and the second NO3 = **Nitrate.
In the NO3-N the value given is for the amount of N or Nitrogen in the test. The O3 has been dropped. In the second it is for NO3, keeping the O3 for the value in the test. The values are the same/say, it is like 25 C vs. 77 F, so you need a conversion number.
10 ppm N-NO3 = 10 x 4.4 (conv. #) = 44 ppm NO3
Lets assume your reading of 15 ppm or is more like 10 and your other reading of 35-40, lets assume 40
15 x 4.4 = 66 ppm
10 x 4.4 =44 ppm
No we have
66 vs 40 and 44 vs 40 (these two almost the same)
The conversion #'s are;
1 ppm NO3-N = 4.4 ppm NO3
1 ppm NO2-N = 2.2ppm NO2
1 ppm NH3-N = 1.1 ppm NH3
Michelle
nitrite poisoning
This is a myth, that nitrite is toxic in seawater. It is quite toxic in FW, although you are often told it is much more toxic in SW. The NO2 ion has to compete in SW with the Chloride ion, Cl-, which will always win. Nitrite is much more toxic in FW and is the reason behind FW systems to add some table salt to reduce Nitrite toxicity.