PO4 - Do you trust your ICPs?

[CasperOe]

Hi Reefers,

I just got back my Triton ICP test which lead me to this question! Do you trust the accuracy for PO4?

ICP - 0 - Zero - Nill
Hanna - 0.10 PPM
Reef Factory Smart Tester - 0.08 PPM

I have been dosing Reef Zlements PhosFate basis the Hanna results to bring it down slightly.

Thoughts?

 

[Garf]

Hi Reefers,

I just got back my Triton ICP test which lead me to this question! Do you trust the accuracy for PO4?

ICP - 0 - Zero - Nill
Hanna - 0.10 PPM
Reef Factory Smart Tester - 0.08 PPM

I have been dosing Reef Zlements PhosFate basis the Hanna results to bring it down slightly.

Thoughts?

Does your hanna and reef factory read fresh RODI saltwater at zero ish?

 

[ryanjohn1]

Realistically you would have to take into account what the plus or minus of your home tests are

 

[CasperOe]

Does your hanna and reef factory read fresh RODI saltwater at zero ish?

They do

 

[CasperOe]

Realistically you would have to take into account what the plus or minus of your home tests are

Sure, that too.

To my knowledge, Triton don't tell you their accuracy either. For less than $1 per element they test, I'd expect some margin for error there as well as well as time in transit etc.

Which one would you rely on?

 

[gbroadbridge]

Hi Reefers,

I just got back my Triton ICP test which lead me to this question! Do you trust the accuracy for PO4?

ICP - 0 - Zero - Nill
Hanna - 0.10 PPM
Reef Factory Smart Tester - 0.08 PPM

I have been dosing Reef Zlements PhosFate basis the Hanna results to bring it down slightly.

Thoughts?

It's not unknown for Phosphorus shown on ICP to be lower than that measured by Hanna or other tests.

It is thought to be due to biological effects occuring within the sample in the time between collection and test, which could be longer than a week.

Many folks including myself use the Hanna result as the most trusted.

 

[exnisstech]

I've only done one ICP test. It was ATI and I have zero confidence in any of the results I received because I also sent two RODI samples in from the same container and received 2 totally different results. There are probably companies that are more accurate or maybe my test were botched in the lab.
Sorry not really what you asked. I can't help with PO4 results because I looked at the RODI results before tank water tests and the different RODI results destroyed my confidence so I didn't pay attention to or even bother saving the tank water results.

 

[ryanjohn1]

Sure, that too.

To my knowledge, Triton don't tell you their accuracy either. For less than $1 per element they test, I'd expect some margin for error there as well as well as time in transit etc.

Which one would you rely on?

I sorta make a ruff average in my head on both. And sorta just look at the corals in the tank. If they look happy and are showing growth leave it be.

 

[Randy Holmes-Farley Verified Community Expert]

I would not generally use P from an ICP sample that sat around for a lengthy amount of time in a closed vial. Comparisons of immediate testing to later ICP can show it to change.

 

[CasperOe]

I will chose to rely mostly on my Hanna checker for this; I even measured the water up using a high precision scale without relying on the line on the side if the glass.

As said before, I have no reason to believe the tank has any phosphate related issues - I was merely wondering about the rather large difference between the three.

My Hanna and Smart Tester are within what's for me considered an acceptable range.

Thanks guys!

 

[rtparty]

Don’t ever use the 10ml lines on the Hanna vials. They are notoriously inconsistent and rarely at 10ml. Use a syringe or pipette for the 10ml and forget about the line.

 

[CasperOe]

Don’t ever use the 10ml lines on the Hanna vials. They are notoriously inconsistent and rarely at 10ml. Use a syringe or pipette for the 10ml and forget about the line.

I use a high precision scale, the same one as I use for calibration of my auto testers taking into consideration the weight difference between RO and SW.

Works out for me the most precise and consistent way.

I have thought about getting a high precision adjustable pipette though to make it somewhat easier..

 

[rtparty]

I use a high precision scale, the same one as I use for calibration of my auto testers taking into consideration the weight difference between RO and SW.

Works out for me the most precise and consistent way.

I have thought about getting a high precision adjustable pipette though to make it somewhat easier..

Weighing it works well. Was just commenting on not trusting the Hanna lines

 

[CasperOe]

Weighing it works well. Was just commenting on not trusting the Hanna lines

Yeah man they're bad - very much depends on your angle as well..

 

[AcanSamDC]

Weighing it works well. Was just commenting on not trusting the Hanna lines

Anyone had bad batches of Hannah reagents? My PO4 is usually around .14, but after two weeks of a fallow tank due to velvet my PO4 tested at .99. Makes no sense as my corals look great, no algae, and hardly feeding. I tested my RO and it also tested around .99. Then I did my tank again and it was .15. Makes no sense at all. I always make sure the glass vials are free of smudges and all that. Totally destroyed my confidence in Hannah. I’m guessing the .15 is accurate but no clue why I got those high readings just before from the same batch of reagent.

 

[TokenReefer]

Doesn't temp affect density?

 

[Pod_01]

From my experience using FM ICP/ FM Total ICP, I never got zero for P or PO4. This is for samples that are on average 2 weeks in transit.
Here is a sample:

Maybe contact Triton and they can re-look at your results.

 

[Randy Holmes-Farley Verified Community Expert]

Doesn't temp affect density?

Why do you ask? You mean for kit volumes?

 

[TokenReefer]

Referring to the weighing of saltwater to find a precise volume (if I understood correctly). I would have thought temp would affect density and weight (and volume) so it would fluctuate depending on the temp

Edit: but the mass would be the same, so it wouldn't?

 

[Randy Holmes-Farley Verified Community Expert]

Referring to the weighing of saltwater to find a precise volume (if I understood correctly). I would have thought temp would affect density and weight (and volume) so it would fluctuate depending on the temp

Edit: but the mass would be the same, so it wouldn't?

The density does vary a bit with temp, but I expect most folks ignore density entirely and just assume 1 g = 1 mL. That’s off by just over 2%, which may be better than most volume measurements folks use.