frustrated with API water test

[goldies88]

I like to say that Nitrate test color chart really mess up . The 40 ppm and 80 ppm color looks exactly the same. Why i color blind

Also is there a expiration date on these water test kit after opened ?

 

[knicks791]

You have to hold it up to the chart against the white part under good light.

 

[Just Prince]

Yes they do expire. Their is a sticky on AC that talks about that in the equipment forum I think. Unless you have a planted tank no nitrates s the way to go.