i have tested my water 3 times tonight with 2 different make kits ....first i tested for nitrate with an api liquid test kit and got 3 readings of 30ppm..


then i immediately ran 3 identical tests with a hagen nutrafin nitrate test kit under exact conditions and got 3 readings of 5 ppm......



has anyone further info on the huge discrepancies between the readings and which do you beleive to be the true reading ????????????

Some liquid test have long life -e.g. pH tests. Nitrates on the other hand might give false readings, but as far as I know when due, nitrates test show less than what actually is present.

This is what I would do. Do a 25% water change. If your tap water is nitrate free, your reading should be 25% less. Measure again with both test to test which one is reflecting reality better.

Pepe
Santo Domingo

I have had a similar thing. I purchased a new nitrate tester as my usual one was running low. I tested with both to find a difference of 10pph. now i am not sure what one is correct??

my point exactly.........i obviously know how to deal with nitrates but the question is which test is correct or how do i find out??????? pepetj..whats - 25% of 30ppm????????????? or 25% of 5ppm??????????????

maybe a third test with another tester is needed to be sure which test kit is right.
if after a 25% water change the new nitrate level should read 22.5 on the one test and should read 3.75 on the other

cheers.......i just done a waterchange so the new readings are 5ppm on one and the other must be about minus 25ppm now !!!!!!!!!!!!!!! LOL LOL

Ok now i am puzzled. I checked my tap water to find that its up by 10pph.the same amount of difference to the 2 kits. now I will do as necro say and buy another kit. i can only guess that the other kit was reading lower or this kit higher.

marcus wrote:



me too............