How long can a testing sample be stored?

[Dom]

More out of curiosity than anything else, if I take a sample of water from a tank, must I test immediately? Will a delay in testing the sample impact the numbers in any way?

 

[Randy Holmes-Farley Verified Community Expert]

Depends on the test. Which tests are you thinking of and how long of a delay?

 

[Dom]

Depends on the test. Which tests are you thinking of and how long of a delay?

Currently monitoring pH, Nitrate, ALK, Calcium and Mag.

Lets say I take a sample in the evening (9pm) but test it the following day around noon.

 

[Randy Holmes-Farley Verified Community Expert]

Currently monitoring pH, Nitrate, ALK, Calcium and Mag.

Lets say I take a sample in the evening (9pm) but test it the following day around noon.

pH would be a big no for that period of delay. Those others are likely fine unless nitrate is very low, in which case a little algae uptake might reduce it noticeably.

 

[Dan_P]

More out of curiosity than anything else, if I take a sample of water from a tank, must I test immediately? Will a delay in testing the sample impact the numbers in any way?

To do things right, refrigerate a sample for a several hour hold period or freeze it if storing overnight. I occasionally monitor 8 or more aquarium experiments at once and sometimes do not have the time (or patience) to do all the measurements at once. Freezing is my first choice.

I saw @Randy Holmes-Farley advice not to delay a pH reading. I never take pH measurements on stored samples. I bite the bullet and get these done immediately.