Question about Nitrates

[f4141]

For topics sake let's use the color yellow as good, orange as "in between", and red as bad.

When I test my tank for Nitrates, it starts out as yellow and then starts to turn orange as time goes by. I also notice that if I shake the vial more after it turns orange, it turns yellow again. If I let the vial sit for about 10 minutes, it turns completely red even when I do 20% (35 gallons) water changes.

My question is, when is the best time to compare the color of the test water to the supplied chart?

Thanks!

Late- Alex

 

[reiverix]

It should say in the instructions how long to wait before comparing with the chart. For the AP test kit it's 5 minutes, after a heck of a lot of shaking.

 

[Kasakato]

You should shake it for 1minute, and let it sit for 5. At the 5 min mark record the number.

 

[Hereford]

I have been checking nitrate daily of late with the notion of optimizing water changes (10-20-40% , weekly, biweekly, or whatever sustains a stable balance.) I use the AP kit and find the color chart gradient very frustrating. The tested water is never exactly the same color (hue? chrominance? depth?) as the card beyond the 10 ppm swatch. Holding the vial between 1/4inch and 1 inch from the card in filtered sunlight, and turning 360 degrees, I can sort of guess that it is probably somewhere between 20 and 80. I bet an art school teacher or interior decorator could match the color precisely, but I sure can't. Does anyone here know of a test kit with a more well-differentiated color scale?

Why be so fussy about stable nitrate? I don't know. Just something to do.