Can I keep API test tubes with water sample overnight?

[FishHobby99]

I am having difficulty reading the nitrate color chart.
Could I store samples from one day to compare to current sample?
Possibly in fridge? Not finding answer online. Did order Xtra tubes from
Amazon.

 

[Uberhoust]

Just by luck I have had 3 tubes of Nitrate tested water which I forgot to clean sitting on my counter. They have been there now for 3 days. It seems to me that the color is not changing after the first 30 minutes but I wouldn't count on it staying the same for an extended length of time. One method might be to take a picture of the sample on the first day then take a picture with the same lighting and background on the next day. I had issues with the nitrate test initially but after you do it a few times you get better at assessing the color. If you have reddish color, then your nitrates are definitely too high.

 

[FishHobby99]

Just by luck I have had 3 tubes of Nitrate tested water which I forgot to clean sitting on my counter. They have been there now for 3 days. It seems to me that the color is not changing after the first 30 minutes but I wouldn't count on it staying the same for an extended length of time. One method might be to take a picture of the sample on the first day then take a picture with the same lighting and background on the next day. I had issues with the nitrate test initially but after you do it a few times you get better at assessing the color. If you have reddish color, then your nitrates are definitely too high.

Thanks! I have been trying to take iPad pics and the lighting is fussy

 

[Slaphppy7]

I wouldn't trust the color results of the test tube samples past the required time to take the test.

Try using this the next time you test, the color-coded cards that come with the API test are sketchy, at best, IME...some colors look exactly the same, and the colors on the card can vary between kits, I have found: https://www.americanaquariumproducts.com/Downloads.html

Just hold the TT next to your display for comparison

 

[FishHobby99]

I wouldn't trust the color results of the test tube samples past the required time to take the test.

Try using this the next time you test, the color-coded cards that come with the API test are sketchy, at best, IME...some colors look exactly the same, and the colors on the card can vary between kits, I have found: https://www.americanaquariumproducts.com/Downloads.html

Just hold the TT next to your display for comparison

Thanks!

 

[Fishmanic]

Are you using the Salifert nitrate test kit I recommended you buy? To read the colors properly, you need to have a strong white lighting such as daylight fluorescent or bright white led lighting.

I find the Salifert test for nitrate much easier to use and is more accurate and easier to read as well.

 

[FishHobby99]

Oh, thanks!!!
Purchased, forgotten & put away. First thing tomorrow.

 

[Fishmanic]

read and understand the directions for use thoroughly...very important

 

[FishHobby99]

Will do. Thanks again.

 

[Fishmanic]

Once you've tried it, let us know how you like the salifert nitrate test kit.

 

[FishHobby99]

 

[Uberhoust]

FYI. Looked at the test tubes that had been left out over a few days now. They appear to have faded since first done. Typical of many dyes exposure to light can cause them to lighten, or react.

 

[Slaphppy7]

FYI. Looked at the test tubes that had been left out over a few days now. They appear to have faded since first done. Typical of many dyes exposure to light can cause them to lighten, or react.

The reagent breaks down over time, and when exposed to light

 

[Bruce Leyland-Jones]

Using the same API test kit, I've noticed colours deepening over time, (a few hours), when I've been distracted from clearing up after myself. I haven't left anything overnight.
All that said, if the colours remained constant, then I'd guess that the instructions telling us when to read the colours would be irrelevant.

 

[Essjay]

One thing I noticed, particularly with the nitrite test, the longer it is left the harder it is to get residue out of the tube. I always wash them as soon as I've finished the test for this reason.