Testing Nitrate with API Test Kit

[mnl119]

So after reading some dismal reviews of the accuracy of the API nitrate test kit, I ordered a Red Sea kit and tested for nitrates in my mixed reef.

Red Sea came back with 20 ppm. I thought the API came back with 5 ppm, but if you look lengthwise down the API test tube, it read 20 ppm as well because the color appears more developed. I know my API copper says to look down the length of the vial to take the reading, but the nitrate test kit instructions do not say to do this. Is it possible that I've just been reading the API wrong all these years?

 

[Seansea]

No. Suppose to look at side of vial up against the card. They arent incredibly accurate but good when u first starting out

 

[Wasabiroot]

If the instructions don't state that then I would assume you've been doing it correctly.

 

[mnl119]

If the instructions don't state that then I would assume you've been doing it correctly.

Well, if I'm doing it correctly by looking cross-wise through the vial, then their terribly inaccurate as judged by Red Sea.

 

[abryant]

So after reading some dismal reviews of the accuracy of the API nitrate test kit, I ordered a Red Sea kit and tested for nitrates in my mixed reef.

Red Sea came back with 20 ppm. I thought the API came back with 5 ppm, but if you look lengthwise down the API test tube, it read 20 ppm as well because the color appears more developed. I know my API copper says to look down the length of the vial to take the reading, but the nitrate test kit instructions do not say to do this. Is it possible that I've just been reading the API wrong all these years?

I used api and my nitrates would always read zero I thought my tank may have been weird or something and then I tried the Red Sea test kit and it was reading 50ppm, no idea how api could be so far off

 

[Reef.]

Well, if I'm doing it correctly by looking cross-wise through the vial, then their terribly inaccurate as judged by Red Sea.

You have used only 2 test kits, why do you assume it’s the API test that is incorrect? I could understand if you had another kit that agreed with the Red Sea.

I use Hanna for nitrate and the API test matches closely to the Hanna, only around 2ppm +/-

Comparing colours is never easy, user error has a lot to do with the result you get, 2 people will likely read the same colour differently.

 

[abryant]

You have used only 2 test kits, why do you assume it’s the API test that is incorrect? I could understand if you had another kit that agreed with the Red Sea.

I use Hanna for nitrate and the API test matches closely to the Hanna, only around 2ppm +/-

Comparing colours is never easy, user error has a lot to do with the result you get, 2 people will likely read the same colour differently.

I just find it hard to believe that anytime I test nitrates it could be zero. I don’t think that’s possible. I don’t think I’m doing anything wrong when I test my nitrates and get zero I just assume it’s cuz it’s a bad test kit I don’t see how red seas test kit could be wrong they’re always reliable

 

[Wasabiroot]

I just find it hard to believe that anytime I test nitrates it could be zero. I don’t think that’s possible. I don’t think I’m doing anything wrong when I test my nitrates and get zero I just assume it’s cuz it’s a bad test kit I don’t see how red seas test kit could be wrong they’re always reliable

That can't be true of any hobbyist grade testing equipment. Occasionally companies make errors. I'm sure they're reliable but every product has duds.
Having at least two different nitrate test kits is good tho

 

[abryant]

That can't be true of any hobbyist grade testing equipment. Occasionally companies make errors. I'm sure they're reliable but every product has duds.
Having at least two different nitrate test kits is good tho

Yeah I see what you mean maybe I got a bad test kit but mine will never read I always get zero I just don’t trust it cuz of that

 

[hexcolor reef]

Nitrate
10drops to 5ml water
Shake a few times
Shake NO3 bottle #2 for 30seconds
Add 10 drops NO3 bottle #2 then shake for 1 minute
Set a 5minute timer then see results.
Make sure you follow every step
I use the reef master kit

 

[Reef.]

I just find it hard to believe that anytime I test nitrates it could be zero. I don’t think that’s possible. I don’t think I’m doing anything wrong when I test my nitrates and get zero I just assume it’s cuz it’s a bad test kit I don’t see how red seas test kit could be wrong they’re always reliable

You will see many threads on here with people asking for help with their nitrates bottoming out, I’m not saying that is your issue but I would check other reasons for your results before I thought it was the test kit, API are big in freshwater too, which is many times the size of the marine world so I wouldn’t consider them inferior to Res Sea.
I have seen more threads on here claiming RS give the same results even when the test sample is diluted.

As the above post say it’s really important to follow the test instructions carefully, API even state in the instructions how important the 30second shaking of the reagent is.
Read the instructions step by step, sometimes are think we are following the instructions but maybe miss out a step, you are also reading the correct colour chart? as the kit has a freshwater card too, obviously you need the seawater chart…if still no luck maybe buy Salifert, it’s cheap and reliable.

 

[Budman93]

So after reading some dismal reviews of the accuracy of the API nitrate test kit, I ordered a Red Sea kit and tested for nitrates in my mixed reef.

Red Sea came back with 20 ppm. I thought the API came back with 5 ppm, but if you look lengthwise down the API test tube, it read 20 ppm as well because the color appears more developed. I know my API copper says to look down the length of the vial to take the reading, but the nitrate test kit instructions do not say to do this. Is it possible that I've just been reading the API wrong all these years?

In about the same boat. i find both the Nitrite and Nitrate almost impossible to gauge. The dark purples look identical for nitrite and the yellows look so similar for nitrate. The only one I can clearly see is ammonia which makes sense since it's green and the human eye sees green the best.

 

[Fritz05]

Another wrinkle: I have 2 API Nitrate test kits, because I bought 2 master test kits. One kit expires in 9/25, the other in 3/26. The "older" kit always tested around 20ppm nitrates, even after several water changes, it never seemed to budge. So I bought a Salifert Nitrate kit and it showed 5ppm. Then I tried the second API kit (exp. 3/26), and it agreed with the Salifert kit (5ppm). So my 2 API kits do not provide consistent results. Btw I tested the API kits at the same time only the about 2 minutes apart needed for shaking and preparing the tests and put the vials next to each other. One was clearly yellow and the other orange.