phosphate reading

[janos]

Hi to all would like to ask if anyone knows what could trow off phosphate reading.Have Hanna phosphorus meter and did not understand Friday my reading was 9 ppb and today is 40ppb.
This happens time to time and could not find out what trows off the meter?What i use is AF np +bacterium,and regular feeding wit frozen cube.Anyone have this experience?Thank you

 

[jsker]

There could be several factors

Time stirring/mixing the cuvette.

Cuvette might have not been clean of residue can throw off the test

Just plain old human error

I have had some off reading and just go back and test later on the next day to make sure.

 

[janos]

Thank you i will try that 2 day later and not give any additive.

 

[Cory]

Any microbubbles will cause it to read higher too

 

[janos]

Any microbubbles will cause it to read higher too

Thank you could that mean i shake the vial to long and than i test and i got micro bubbles ?

 

[Randy Holmes-Farley Verified Community Expert]

It might be a real change in the water (from phosphate in foods, for example), or a test error in one or both of them. There's no good way to tell after the fact.

 

[janos]

It might be a real change in the water (from phosphate in foods, for example), or a test error in one or both of them. There's no good way to tell after the fact.

Thank you Randy try to wait for 4-5 day not to give any additive not feed the fish and corals and let see a clean test.Thank you again

 

[Cory]

Thank you could that mean i shake the vial to long and than i test and i got micro bubbles ?

No. I mean that if there are microbubbles stuck to the glass they will cause a higher reading because they reflect more light. At least thats how I understand it. But too many bubbles in the sample will also cause a false reading.

 

[Cory]

Thank you could that mean i shake the vial to long and than i test and i got micro bubbles ?

Double post

 

[janos]

Double post

Thank you Cory,try to look for every small thing because do not understand Friday morning i read 9 ppb and Sunday read 35 ppb .I feed the fish every day with 2 cube and i give lot of additive to the thank. NP pro,Pro bio S,Polyp booster ,reef roid,that is why i ask what could trow off the reading.Thank you for your time.