Chemistry changes if sample is left out for an hour or two?

[mike550]

I’d like to measure my water chemistry at 6:00 in the evening to be consistent. But if I draw the sample at 6:00 and leave it sit in a glass until 8:00 will the water parameters change?

Measuring alk, Ca, Mg, phosphates, nitrates if it matters

 

[rastareefs]

There are plenty of testing companies that require you to send in samples via mail so you should be fine.

 

[mike550]

There are plenty of testing companies that require you to send in samples via mail so you should be fine.

Thanks! I didn’t even think of that. Much appreciated

 

[Quietman]

I think it's probably more a factor of how much evaporation and contamination you could have with open jar. But yes, I wouldn't think it'd be much for 2 hours.

 

[Randy Holmes-Farley Verified Community Expert]

Those parameters won’t substantially change. Others like pH and ORP will.