Salifert nitrate test kit.

[Pennywise the Clown]

After a Dino outbreak I have been trying to raise my nitrates. When I test for nitrates and wait for the recommended 3 minutes the reading is always very low, less than 1. But if I leave the test vial sitting for an hour I get a reading of around 10.
Which is correct?

 

[Waters]

According to the instructions, it can be read at the 3 minute mark so I would go with that reading.

 

[Randy Holmes-Farley Verified Community Expert]

All kits should be evaluated at the exact time (and temp, if stated) that the manufacturer recommends. Many reactions will continue in such kits, but that is not improving the accuracy.

 

[Potatohead]

I would assume what is in the instructions is correct, that time is specified for a reason.