need help with nitrate testing.

[Art2249]

I'm really baffled by my nitrate results. I have 2 tests, API and Red Sea Pro. The API reads 80 ppm and the Red Sea reads 8 ppm (I am using the high range 1 to 15 dilution). I am doing a water change today and have some fresh salt water on hand. I tested it with API and it read zero. So I tried an experiment and used the fresh water to dilute my sample for the Red Sea test. The first time I used 50/50 tank water to new salt mix. The results came back at 4 ppm. This is consistent with the high range results as per instructions using RO water to dilute. I ran the test again with a 1 to 4 dilution of tank water to new water. The results came back at 2 ppm as expected. i just find it hard to believe that the API test could be that far off. The tank looks good other than some hair algae. I even have some acropora that is colored up and growing. I just got my Nopox in today and plan on switching over from vodka but i'm not sure how I should do that. Anybody have any suggestions?

 

[BeejReef]

I generally love RS tests, but I do dislike the nitrate test. Not only the need to run a separate (9 minute) test for the low and high range, but also the fact that the cutoff is 4ppm. Really inconvenient since so many try to hold N between detectable and 10ppm. I love the salifert. Low and high range all in one test. Look through the top of the vial for high, through the side for low. At least to my eye, the color match on the low range really pops, and at that point you're deciding between one and 2.5 anyhow.

This stuff is really useful. Two tests enter, one test returns to the fish cabinet and the other is exiled.

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