# API liquid tests, wait 5 mins, how long results good for?



## WaterLife (Jul 1, 2015)

Using the API freshwater master test kit.

You know how it says to wait 5 minutes (for color indicator solution to mix) before reading test results (Ammonia, Nitrite, I think Nitrate too), well I was wondering if there is any time limit to check the test results.

For example, sometimes when I test tank water, while the tests are waiting that 5 minute period, I am busy doing other tank duties and so, sometimes I don't get around to checking the test results until 10-15 minutes later (even sometimes longer). I do try to check as close to the 5 minute mark most of the time, just sometimes I don't. So I was wondering if the test results are still reliable/valid after how many minutes, or hours even, after the liquids were mixed.


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## lksdrinker (Feb 12, 2014)

I dont think they ever really "expire" its just they need at least 5 minutes to give an accurate reading. the longer you wait the more accurate the result probably is. I'd avoid leaving them in too long (say overnight or more) as they liquids end up staining the test tubes sometimes.


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## mattinmd (Aug 16, 2014)

Some of the tests do "expire", at least if you leave them for extended periods of time (hours).

For example, If I leave my API phosphate tests laying out overnight they turn cloudy and form some kind of precipitate by morning. 

Several other tests will also have their colors fade or intensify if left too long. I forget which ones do what, but IIRC API ammonia tests fade, and nitrate darkens.

I forget to rinse a tube or two fairly often, and have yet to find an aquarium test that will stain glass tubes.... Are you adding hydrofluoric acid to your tests lksdrinker?


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## lksdrinker (Feb 12, 2014)

mattinmd said:


> I forget to rinse a tube or two fairly often, and have yet to find an aquarium test that will stain glass tubes.... Are you adding hydrofluoric acid to your tests lksdrinker?


LOL nope! Just the standard API liquids and I've got at least 2 test tubes that I try not to use as one shows a tinge of green and another a tinge of yellow which I believe were both due to doing an ammonia test and not rinsing the tubes out for a couple of days.


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## Oso Polar (Apr 22, 2015)

Ammonia, nitrite, nitrate tests maintain their color for hours. Phosphate test doesn't - some precipitate appears quite fast, in a matter of minutes, so I'd not wait too much with this test.


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## WaterLife (Jul 1, 2015)

Thanks for the answers everyone!


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## Diana (Jan 14, 2010)

I have seen some of them keep on changing color beyond the stated limit. 
I would try to read them all within 30 seconds (plus or minus) of the limit.


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## Maverick2015 (Aug 8, 2015)

I have often forgot about my tubes and the API tests still showed the same color. pH might be the only one I would question.


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