Hanna ulr phosphorus test results

[Trooper182]

May be a crazy question. So I noticed when testing with the ulr tester, I follow the directions and press the button to cycle the 3min countdown before the rest is run. When I get the results it shows whatever it tests at ppb. But if I let the sample sit for say ten min and run the test again the result is consistency higher than the first test. I have tried this a few times when testing and each time the number is higher vs the first reading it gives me. And not just a little higher. So what gives?

 

[Waters]

That is true with most of the titration tests. That is why there are specific time limits for each test. They tend to darken the longer they sit.

 

[Gadbery]

May be a crazy question. So I noticed when testing with the ulr tester, I follow the directions and press the button to cycle the 3min countdown before the rest is run. When I get the results it shows whatever it tests at ppb. But if I let the sample sit for say ten min and run the test again the result is consistency higher than the first test. I have tried this a few times when testing and each time the number is higher vs the first reading it gives me. And not just a little higher. So what gives?

Test is designed to be ran after 3 min. Waiting even longer means the chemical reagent has longer to sit scewing the result. Same concept as peeing on a pregnancy's test and leaving it for an hour itll turn to a positive cause its meant to be read in 90sec (ya been through that scary crisis.)

If you are concerned grab another test kit from another brand to compare it to.


I also assume when you retest your testing (initial test with another tube of straight tank water.)

 

[taricha]

Some reactions are color stable and some are not. Some lose color, gain color, change colors altogether after their intended reaction is done. This doesn't mean they are measuring anything better - it just means the reaction products aren't stable and shouldn't be used after the set time.