ICP Phosphorous/Po4 Vs. Hanna Po4 Tests

[Moe K]

So I am battling some LCA dinos in the sand bed and while trying to monitor my Po4 and nitrate I am getting mixed results between my Hanna Po4 ulr tests and the results from icp-analysis. I am consistently getting results from the hanna that read 0.08 to 0.10 ppm. The icp analysis tests show much much lower for po4 and phosphorous. I would rule out once or twice that icp analysis is just not reliable on those parameters but it appears to be consistent results. I also bought a new salifert po4 test kit and it is also showing me closer results to the hanna tests at a higher value.

Here are the ICP Analysis results

The dinos did appear in full force in February. I have dosed silicates a few times but nothing too crazy I believe so it should not throw off any Hanna tests or should it? Also the salifert test I was told is not affected as much by high silicates and it also reads more consistent with a higher value.

Silicon/silicates?

Should I get a Hanna Phosphorous tester for more accurate results??

 

[Dan_P]

So I am battling some LCA dinos in the sand bed and while trying to monitor my Po4 and nitrate I am getting mixed results between my Hanna Po4 ulr tests and the results from icp-analysis. I am consistently getting results from the hanna that read 0.08 to 0.10 ppm. The icp analysis tests show much much lower for po4 and phosphorous. I would rule out once or twice that icp analysis is just not reliable on those parameters but it appears to be consistent results. I also bought a new salifert po4 test kit and it is also showing me closer results to the hanna tests at a higher value.

Here are the ICP Analysis results

The dinos did appear in full force in February. I have dosed silicates a few times but nothing too crazy I believe so it should not throw off any Hanna tests or should it? Also the salifert test I was told is not affected as much by high silicates and it also reads more consistent with a higher value.

Silicon/silicates?

Should I get a Hanna Phosphorous tester for more accurate results??

Ignore the ICP results for phosphorous. It is one of the elements that the hobby ICP business struggles to measure. Also, unlike the Checker test, ICP vendors never provide accuracy information about the results.

 

[gbroadbridge]

So I am battling some LCA dinos in the sand bed and while trying to monitor my Po4 and nitrate I am getting mixed results between my Hanna Po4 ulr tests and the results from icp-analysis. I am consistently getting results from the hanna that read 0.08 to 0.10 ppm. The icp analysis tests show much much lower for po4 and phosphorous. I would rule out once or twice that icp analysis is just not reliable on those parameters but it appears to be consistent results. I also bought a new salifert po4 test kit and it is also showing me closer results to the hanna tests at a higher value.

Here are the ICP Analysis results

The dinos did appear in full force in February. I have dosed silicates a few times but nothing too crazy I believe so it should not throw off any Hanna tests or should it? Also the salifert test I was told is not affected as much by high silicates and it also reads more consistent with a higher value.

Silicon/silicates?

Should I get a Hanna Phosphorous tester for more accurate results??

Trust the Hanna checker.

Between the time you take the sample and the ICP test, there is likely biological phosphate reduction in the sample.

What you are seeing is quite common.

 

[Pod_01]

Just observation, the ICP lab does definitely like lot of decimal points. Not sure if all of those numbers are useful.
I would pick lab that uses fewer decimal points, since that might indicate they understand the reefing needs and the ICP machine limitations.

ICP machine measure element P and from that the lab can calculate total PO4.

All of the test kits measure orthophosphate PO4 and it is one of the forms that can be in the reef tank.

You are comparing apples and oranges. But total PO4 should be higher or equal to Ortho Phosphate.

Here is example of a ICP lab that shows all 3 phosphates types:

Also depending on Hanna checker the accuracy is +/-0.02 ppm so that needs to be accounted for as well.

My suggestion is to use what Hanna shows. If Hanna results get below 0.05 you might have depleted your PO4.

There is more than PO4 and NO3 to help to deal with Dino’s, for example your tank light level might be one of them. Keeping PO4/NO3 levels stable is also important, if they keep swinging that leads to undesirable results. Over filtration can be an issues. How are the other parameters like salinity?

How are the corals doing? They can help with undesirables and make the tank stable. Coral mass and hardy corals like GSP can help a lot, just keep it on its own rock because it can become a pest.

 

[Randy Holmes-Farley]

I would also suggest that it is not that ICP is not itself good at measuring P, but that P can change during transit unless there is something in the vial to halt growth of microorganisms.

 

[Moe K]

I would also suggest that it is not that ICP is not itself good at measuring P, but that P can change during transit unless there is something in the vial to halt growth of microorganisms.

That makes sense that biological activity is changing the results during the transit time. Probably more so in warmer weather. Would the phosphate be converted to something else that would show elevated in the icp tests?

 

[Randy Holmes-Farley]

That makes sense that biological activity is changing the results during the transit time. Probably more so in warmer weather. Would the phosphate be converted to something else that would show elevated in the icp tests?

The concern is uptake into bacteria or algae, which are often attached to vial walls or removed by centrifuge before analysis.

All forms of P entering the plasma will be detected.