Phosphate: Redsea vs Hanna

Trevorreilly73

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Hi reefers, I recently got a Hanna ulr phosphate checker. Originally I was using Redsea phosphate test.

On the Redsea test I get no colour change whatsoever.. leading me to believe I have no phosphate.

Using the hanna checker I have 0.27ppm phosphate.. leading me to believe I have way too much.

Has anyone any experience/advise on this?
 
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Trevorreilly73

Trevorreilly73

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Randy Holmes-Farley

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A great question, one I never thought of myself. What is the purpose to testing a batch of freshly mixed saltwater? Contamination coming through the rodi system?

It’s mostly to test the test itself, but it can also point to an ro/di problem.
 

hsp

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I have a HI774 and noticed weird changes in my tank. So, I did 3 tests in rapid succession using exactly the same methodology as per instructions and got the following results:

0.12ppm

0.06ppm

0.08ppm

I shared this with Hanna support and was told:

Have you considered the following:
  • Are there any scratches/marks on the vials? You may need to purchase new vials
  • Are you ensuring there are no finger marks or that the vial is wiped dry properly?
  • Have you verified using the calibration check set i.e. HI774-11?
  • Have you done 3 tests of the same sample taken? The accuracy of the checker is ±0.02 ppm ± 5% of reading.
Failing all the above attempts, you may have to purchase a new replacement as the HI774 checker is out of warranty.

I think in my case some scratches on the vials caused the issue.
 

Dburr1014

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Hi reefers, I recently got a Hanna ulr phosphate checker. Originally I was using Redsea phosphate test.

On the Redsea test I get no colour change whatsoever.. leading me to believe I have no phosphate.

Using the hanna checker I have 0.27ppm phosphate.. leading me to believe I have way too much.

Has anyone any experience/advise on this?
I could never get a good reading with redsea either.
Hanna is they way to go if you can.
 

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