Correct way to read nitrate levels?

[Luananeko]

Okay, so I've been using my API master test kit for several years now, and I STILL can't figure out the right way to read the nitrate test's color. I figure it's high time I ask and see how everyone else reads it. I follow the directions to the letter about shaking the bottles first, yada yada, but once it changes colors I can never tell what color on the key it's matching to.

No, I'm not colorblind. The color seems to vary wildly depending on the angle it's held at, the lighting, whether I hold it up directly against a white paper, further away from a white paper, etc. The same reading looks anywhere from 20 ppm to 160 ppm (highest the chart goes) depending on these factors. What's the right way to do it?

It's gotten to the point that I just throw up my hands and do 50% water changes every week regardless of what the readings say... While I agree that's best for the fish anyways, it's murder on my water bill...

 

[Delapool]

Er, I read it against the chart (upside down) and against white background.

I seem to pick it better with the chart upside down, bit weird.

Half the colours look the same to me.

 

[Pandicorn]

I use it against white background, with my lamp giving some bright light. Agree though, colors too similar

 

[mrvincent]

Shake and bang nitrate bottle #2 like hell for the most accurate readings straight before you put drops in the sample, it tend to give a lower value else...

If you have difficulty to read shades of yellow to red to brown, maybe ask for a friend to read it.

It's easy to read between 5ppm to 40ppm, but over >60ppm all colors will seems the same... Anyways if NO3 > 40ppm, you have to find the problem.

 

[Krogman]

I like to test mine prior to and after my WC, and do find it difficult sometimes. I hold in good sunlight and hold it against the white on the chart. In my log I tend to put 0, 5-10, 20-40, or >40.
I too had just decided to do weekly 50% changes. However after a long two weeks and no WC, I tested my nitrate twice and got 0 both times. There may and I mean MAY have been the tiniest slightest orange in one test but closer to 0 than anything. Maybe due to a large increase in plants nitrates were absorbed.
Also it helps that my water bill is covered by my landlord all four apt share the same meter so landlord pays it

 

[Luananeko]

Shake and bang nitrate bottle #2 like hell for the most accurate readings straight before you put drops in the sample, it tend to give a lower value else...

If you have difficulty to read shades of yellow to red to brown, maybe ask for a friend to read it.

It's easy to read between 5ppm to 40ppm, but over >60ppm all colors will seems the same... Anyways if NO3 > 40ppm, you have to find the problem.

See, thats what I do already. I can identify which color it is, but the the color itself drastically changes depending on several factors. The same sample can read:
1) Held up next to the chart but with nothing behind it other than a white wall a few feet away - 20 ppm
2) Same scenario as above but with light in front of me instead of behind me - somewhere between 40-80 ppm, those colors all kinda blend together
3) Held horizontally with a white paper an inch from the back - ditto above
4) Held horizontally on top of the white section of the chart - somewhere between 80-160 ppm

Which way is right? It's good to hear I'm not the only one having issues reading the darn colors though...

 

[PerfectDepth]

Maybe this will help:

 

[Luananeko]

Hard to say since every monitor displays colors differently, but I THINK holding the vial up with a white wall a few feet away gives similar results to that picture... When I hold things up near the vial it starts varying colors from the edges toward the middle due to refraction. Stupid glossy finish glass ...

Edit: You can see a little bit of what I mean even in that picture though. Look at the first two vials, theres a brighter strip on the right edge of them due to the way the light is refracting. The darker ones are shielded from the light more by the first few vials, so you don't see the same effect.

 

[PerfectDepth]

Edit: You can see a little bit of what I mean even in that picture though. Look at the first two vials, theres a brighter strip on the right edge of them due to the way the light is refracting.

Right, it can be very difficult to discern the different colors until you get used to it. Try to train yourself to see it as the same color whether it's brighter or darker - in other words, pay attention to the hue, and disregard the brightness. Think in terms of yellow/red instead of bright/dark.