I've been trying to keep a close eye on my nitrate levels on my 55gal ciclid tank. My test kit says to keep below 110ppm or mg/l. I read to keep it below 50ppm for african ciclids. So I'm trying like crazy to keep it in check, doing weekly water changes with no success. Then I find out that there is two means of measuring for nitrates. One as a nitrate-ion and one as nitrate-nitrogen. My test kit gives a conversion for nitrogen(divide result by 4.4) so I'm figuring it's measuring nitrate-ion. So when I read to keep my tank under 50ppm what scale is that? People and even manufacturers of test equipment throw around nitrate numbers all the time without distinguishing what they are talking about. What, if any, is the standard? What is a good target level for a healthy ciclid tank? Who makes a good test kit that measures for nitrogen(is that the more important figure?). Can somebody clear this up. I've had a pretty successful aquarium for the last year or so and now I find myself stressing over water perameters that I might not even be interpreting correctly.