Hanna Checker PO4 confusion

Never too many · Jan 8, 2023

I just purchased a Hanna Checker Phosphate tester. I have ran 2 tests on 2 of my tanks, a day apart . My 90 comes back with an 8 ppb and 9 ppb (0.024-0.028 ppm), but on both days my 55 gets the flashing 200 ppb (result exceeds 0.613 ppm). This could also mean that the results were skewed due to dirty vial or debris in the sample. I did make sure to avoid both of those possibilities on the second day. I am being very careful to follow the exact procedure with both tests. When I used my Nutrafin/Hagen test my results both tanks show in the color range somewhere around 0.25-0.5 (thus I hate color charts). The only thing that I have done different between the 2 tanks is that I have recently added a chaeto reactor to the 90, and did half of the minimum recommended dose of Brightwell Aquatics Phosphate-E to the 55 about 2 weeks ago. I guess that I am wondering if the phosphate remover could be affecting the results of the test that much. Any feedback on this would be greatly appreciated.

Miami Reef · Jan 8, 2023

Never too many said:
I just purchased a Hanna Checker Phosphate tester. I have ran 2 tests on 2 of my tanks, a day apart . My 90 comes back with an 8 ppb and 9 ppb (0.024-0.028 ppm), but on both days my 55 gets the flashing 200 ppb (result exceeds 0.613 ppm). This could also mean that the results were skewed due to dirty vial or debris in the sample. I did make sure to avoid both of those possibilities on the second day. I am being very careful to follow the exact procedure with both tests. When I used my Nutrafin/Hagen test my results both tanks show in the color range somewhere around 0.25-0.5 (thus I hate color charts). The only thing that I have done different between the 2 tanks is that I have recently added a chaeto reactor to the 90, and did half of the minimum recommended dose of Brightwell Aquatics Phosphate-E to the 55 about 2 weeks ago. I guess that I am wondering if the phosphate remover could be affecting the results of the test that much. Any feedback on this would be greatly appreciated.

Let the sample of water sit for a few hours, so any lanthanum phosphate precipitation can settle. Then, draw up the syringe from the top of the sample.

The only time lanthanum phosphate will cause a false positive is if any of the precipitation gets in contact with the phosphate reagent, which is an acid that can dissolve the lanthanum-phosphate bond, which releases the “removed” phosphates.