How do you ensure accurate WC testing?

[Fishjayfonz]

Hey all,

Curious to see how others test their systems to ensure accurate results for example by running multiple series, standards, brands etc.

Currently I use the AF kits for Ca & Mag, and Hanna Checkers for Alk & PO4. Recently I've been trying to fine tune my testing methods to ensure the numbers I'm getting are reliable. I'll check readings by running Ca & Mag using Salifert kits as well as running samples against a standard provided in the AF kits for Ca & Mag. I'll also send off a monthly ICP when I can.

Lately I have become distrusting of the ULR Hanna checker for PO4 as it's readings conflict with ICP (~0.30 checker vs. 0.02 ICP), so finding a way to reliably test for PO4 is my priority right now, without having to rely on external ICP testing.

Would love to hear your guys methods and how you drive for precision!

Fair Winds & Happy Reefing,

Jason

 

[Randy Holmes-Farley]

I agree, we can only get so accurate with hobby grade kits but trends are better indicators anyways.

I have consistently gotten very different readings specifically for PO4 between the hanna checker and ICP so figuring out which trend to rely on has been my issue

I'd just be wary of concluding that indicates a test problem at either end as the water is sitting around for days or weeeks before testing, changing in ways that may be detectable as organisms in the water grow and die, and as precipitation of some components may be hard to detect.

 

[workhz]

Do you pour from the packet and shake the same way for 2 minutes (or whatever the time is) prior to putting in egg?

Might be more consistent to put the content of the packet (all of it) in something else prior to dropping into vial.

 

[Fishjayfonz]

Have you run PO4 standards in PO4 Checker and ICP? Unless you do that, it is impossible to say which test is more accurate.

I have made standards in the past but have found that they tend to drift in readings quite a lot over a period of a few weeks. ICP we use Triton and am fairly confident in those results as our Iodine is also in check. Would like those results to agree with our in house testing though

 

[Fishjayfonz]

Change the batteries of your Hanna PO4 with brand new ones.
If you use lanthanum chloride, the Hanna will read higher. Happened a bunch of times to me.

I have used lanthanum only once about a year ago, could it have that long of an effect? I'll change the batteries and run a series as I do believe its a problem with the checker first.

Thank you

 

[doubleshot00]

I'm all about consistency. Test the same time of the day and the same day every 2 weeks is how I do it. If I miss the mark wait till the next day at the same time.

My Hannas are usually spot on. I have found a few packets of the Nitrate and Phosphate ULR to be a bit off; I just do another test with a different packet or have a Salifert/Red Sea kit as a back up.

My ICP is always different than my test but also the water has been in transit for a week then sitting in a lab for a week. Just saying. Couldn't that effect the test?

 

[Fishjayfonz]

I'd just be wary of concluding that indicates a test problem at either end as the water is sitting around for days or weeeks before testing, changing in ways that may be detectable as organisms in the water grow and die, and as precipitation of some components may be hard to detect.

Would that mean ICP results could be artificially high? I'm concerned that there is PO4 deficiency as I do not do coral feeds/ run ozone + carbon. But since I am regularly testing very high in-house, I'm wary of doing bigger feeds

 

[Fishjayfonz]

I'm all about consistency. Test the same time of the day and the same day every 2 weeks is how I do it. If I miss the mark wait till the next day at the same time.

My Hannas are usually spot on. I have found a few packets of the Nitrate and Phosphate ULR to be a bit off; I just do another test with a different packet or have a Salifert/Red Sea kit as a back up.

My ICP is always different than my test but also the water has been in transit for a week then sitting in a lab for a week. Just saying. Couldn't that effect the test?

Bump to Randys comment about ICP samples sitting for very long.

What do you use to checker your PO4 readings against the checker? I use A HACH 6000 here but find it very inaccurate at the ranges needed for reefing

 

[doubleshot00]

Bump to Randys comment about ICP samples sitting for very long.

What do you use to checker your PO4 readings against the checker? I use A HACH 6000 here but find it very inaccurate at the ranges needed for reefing

Salifert has been spot on for me.

 

[Dan_P]

I have made standards in the past but have found that they tend to drift in readings quite a lot over a period of a few weeks. ICP we use Triton and am fairly confident in those results as our Iodine is also in check. Would like those results to agree with our in house testing though

Unfortunately, ICP values are not stable either. They vary for multiple reasons that the ICP vendors are not quite upfront about. If you are trending data, in house test results tends would be the data to trust. I would never use ICP test results as a validation of in house test results.

 

[Marinexx]

With an accuracy of +/- 0.02 ppm, the only odd reading seems to be 0.02 ppm. Just imagine what your “readings” would be using a kit with a color chart :)

Are your vials scratch free? Do you always place the vial in the Checker oriented in exactly the same way? I am trying to come up with ideas that might up your game.

Agree with assessment that 0.02 only outside reading.

What do you mean by placing the vial oriented in exactly the same way?
Personally, I clean the vial before each use so it is without spots and streaks. My readings have been spot on with Hanna PO4 and ICP ATI

 

[vetteguy53081]

Hey all,

Curious to see how others test their systems to ensure accurate results for example by running multiple series, standards, brands etc.

Currently I use the AF kits for Ca & Mag, and Hanna Checkers for Alk & PO4. Recently I've been trying to fine tune my testing methods to ensure the numbers I'm getting are reliable. I'll check readings by running Ca & Mag using Salifert kits as well as running samples against a standard provided in the AF kits for Ca & Mag. I'll also send off a monthly ICP when I can.

Lately I have become distrusting of the ULR Hanna checker for PO4 as it's readings conflict with ICP (~0.30 checker vs. 0.02 ICP), so finding a way to reliably test for PO4 is my priority right now, without having to rely on external ICP testing.

Would love to hear your guys methods and how you drive for precision!

Fair Winds & Happy Reefing,

Jason

I use trident tester and verify readings with hanna marine master kit

 

[Dan_P]

Agree with assessment that 0.02 only outside reading.

What do you mean by placing the vial oriented in exactly the same way?
Personally, I clean the vial before each use so it is without spots and streaks. My readings have been spot on with Hanna PO4 and ICP ATI

The vial can be turned in the Checker 360 degrees. The same orientation refers to always placing the vial facing the same way. The effect might be small though.

 

[s70]

I use the hanna ulr phophate checker and get readings as follows with the same sample.
1st 0.09
2nd 0.02
3rd 0.06
4th 0.06

I started running multi tests when I had a reading of 0.01 down from the previous days check of 0.09... to me it is all over the shot. I do the exact same procedure everytime so I would expect more consistency. I am not chasing a specific number hard and fast, but more the trend

I was also at the low end on PO4 and switched to testing Phosphorus and making the conversion to PO4. I think it tests lower range better.

 

[Fishjayfonz]

I was also at the low end on PO4 and switched to testing Phosphorus and making the conversion to PO4. I think it tests lower range better.

I used to use the phosphorus checker as well, going to run a series of kits today and see what i can find thank you

 

[Fishjayfonz]

I use trident tester and verify readings with hanna marine master kit

Been looking at getting this set, how do you find it?

 

[vetteguy53081]

Been looking at getting this set, how do you find it?

https://www.hannainst.com/marine-master-waterproof-wireless-multiparameter-photometer-hi97115.html?msclkid=9a497dc019101e440f43194c7e49a8f4&utm_source=bing&utm_medium=cpc&utm_campaign=CPCS+-+Shopping+-+Catch+All+-+%5BB%5D&utm_term=4582214710053920&utm_content=All+Products

Marine Master HI97105 Multiparameter Photometer

Accurately check pH, Alkalinity, Calcium, Low Range and High Range Nitrate, Ultra Low Range Nitrite, and Ultra Low Range Phosphate with one single, compact multiparameter tester! All-In-One Testing with Precise Results for Reef TanksThe HI97105 Marine Master Photometer is a waterproof tester...

www.bulkreefsupply.com

 

[Randy Holmes-Farley]

I have used lanthanum only once about a year ago, could it have that long of an effect?

Thank you

No. Any concern relates to particulates of lanthanum phosphate sill in the water that might get into and dissolve in phosphate tests.

 

[Randy Holmes-Farley]

Would that mean ICP results could be artificially high?

Could be either one, depending on what happens to the sample and how it is prepper for the ICP. Do whole bacteria enter the ICP sample itself? Maybe.

 

[Rick Mathew]

Nothing like a little investment in glassware couldn’t fix :)

@Rick Mathew do you have better choice, something that doesn’t require glassware or belonging to an institution? What about a multi parameter option?

Dan, I do not know of any real shortcuts to setting up standards. If one really wants to evaluate the precision and accuracy of any test and feel confident in there results, then multiple levels of the element being tested are necessary. Usually I prepare samples (Standards) over the range that I would expect results. As an example, when I did the accuracy and precision work on the HI-758 Calcium Checker I made standards at 300 ppm 350 ppm 400 ppm 450 ppm and 500 ppm (Here is a link to the work https://www.reef2reef.com/threads/calcium-reading-crazy.769786/#post-8120963 )

This all requires that ability to make accurate standards which in turn requires the equipment to do so. This starts with the ability to find certified standards to start with. As you know this is no easy task. Hach makes some but not all of the elements for seawater testing. I get my standards from a distributor of Inorganic Ventures called TSP (Texas Scientific Products), but they will not ship them to a residential address only a business address. They are also quite pricey because they are NIST certified standards that are used for things like ICP calibration...Here is a link to their website https://www.txscientific.com/new-products-c34.aspx

Once the standards are available a set of volumetric flasks, some good pipettes and a set of graduated cylinders and your off to a good start.

It is also possible to make the standards from reagents and get reasonable results, like Calcium standards from Calcium Chloride. It is best to use reagent grade chemicals. This also requires a very accurate scale to prepare the standards along with the other glassware.

Rick

 

[Rick Mathew]

Hey all,

Curious to see how others test their systems to ensure accurate results for example by running multiple series, standards, brands etc.

Currently I use the AF kits for Ca & Mag, and Hanna Checkers for Alk & PO4. Recently I've been trying to fine tune my testing methods to ensure the numbers I'm getting are reliable. I'll check readings by running Ca & Mag using Salifert kits as well as running samples against a standard provided in the AF kits for Ca & Mag. I'll also send off a monthly ICP when I can.

Lately I have become distrusting of the ULR Hanna checker for PO4 as it's readings conflict with ICP (~0.30 checker vs. 0.02 ICP), so finding a way to reliably test for PO4 is my priority right now, without having to rely on external ICP testing.

Would love to hear your guys methods and how you drive for precision!

Fair Winds & Happy Reefing,

Jason

Here is some information supporting Randy's comment ...https://www.reef2reef.com/ams/sample-storage-and-its-impact-on-measurement-results-part-3.800/

You will find some of the explanation of "why" here