Testing, Testing . . . 1 2 3

[esther]

OK, so it's water test day... Wondering what you all make of these numbers (keep in mind we did all tests twice, just to be sure). My biggest issue is Alkalinity. We're going to retest today after we recalibrate our KH Director to see if it ends up closer to our Hanna tester. Which ones do we trust? Which tests should we throw in the garbage? Thanks in advance for the input. Also, going to send out for ICP tests today as well to get more detailed info.

Alkalinity
KH Director (we're going to recalibrate today.. Just set it up yesterday) : 7.2 dKH
Hanna : 8.5 dKH
Red Sea : 11.2 dKH

Phosphate
Hanna : 0.86 ppm

Nitrate
API : 0 ppm
Salifert : 10ppm

Calcium
Hanna : 480ppm
Red Sea : 525

Magnesium
Red Sea : 1,500ppm

Nitrite
API : 0 ppm

Temperature
Profilux Probe : 78.6

pH
Profilux Probe : 8.18
Cheap Amazon pH pen : 8.49

Redox
Profilux Probe : 337

Salinity
Profilux Probe : 1.0247
Hanna : 1.026

 

[mike550]

@esther I can offer a few thoughts for you.

I’ve tested my Hanna Alk side by side someone else testing using Salifert. We were spot on. So I’d keep the Hanna Alk measurement.

I’m surprised by your Nitrate readings. I just tested nitrate using Salifert and Red Sea and both were within 5ppm of each other.

I really like my Hanna salinity checker — and it gives you another temp measurement also. But if you round Profilix you’re at 1.025 and Hanna at 1.026. I’d be comfortable with either one.

 

[esther]

@esther I can offer a few thoughts for you.

I’ve tested my Hanna Alk side by side someone else testing using Salifert. We were spot on. So I’d keep the Hanna Alk measurement.

I’m surprised by your Nitrate readings. I just tested nitrate using Salifert and Red Sea and both were within 5ppm of each other.

I really like my Hanna salinity checker — and it gives you another temp measurement also. But if you round Profilix you’re at 1.025 and Hanna at 1.026. I’d be comfortable with either one.

To be fair, the API test that we're using for Nitrate is that little dipper stick one that has 5 tests on it. So, I'm thinking that the Salifert one is probably closer to accurate. We currently have 0 livestock in the tank, so I think once we add some corals, it should drop down a little, right?

 

[Quietman]

If you want to develop trust in your test equipment and your interpretation of the readings you're going to need to run some tests on known standards. Comparing one test kit to another in the hopes that one is more accurate isn't going to be a productive use of time. These test kits are very consistent (meaning repeatable for same kit, not necessarily between each other) but only when you know what the responses are for a given input. For example, my Hanna Alk reads about .2 higher than the standard always, my Red Sea Alk (until I adjusted what I consider a solid color change) was off by as much as .7 always. That's not to say that one is more accurate than the other, that's a marginal difference really, it's how we perform the test and read the results. So I can now use both Hanna and Red Sea with confidence but I now know how to correctly interpret each of their readings. The Hanna is nice because it does take out some our 'eye balling' but it's still going to have an error due limitations of the test.

Get some standards (several offered on BRS from specific element to overall seawater) and then you'll be able to have a lot more confidence in the results.

 

[Rick Mathew]

@Quierman is right on with regard to accuracy....Accuracy and Precision are the two key elements to having confidence in your test results. I have spent a great deal of time on answering this question for myself....Here are 4 articles that describe my quest for reliable results..

PART 1 https://www.reef2reef.com/ams/getti...count-by-using-a-quality-system-approach.741/

PART 2 https://www.reef2reef.com/ams/part-...tem-approach-colorimetric-visual-testing.744/

PART 3 https://www.reef2reef.com/ams/part-...etric-visual-testing-methods-what-we-see.747/

PART 4 https://www.reef2reef.com/ams/part-...ric-instrumental-testing-methods-digital.748/

Rick

 

[Rick Mathew]

If you want to develop trust in your test equipment and your interpretation of the readings you're going to need to run some tests on known standards. Comparing one test kit to another in the hopes that one is more accurate isn't going to be a productive use of time. These test kits are very consistent (meaning repeatable for same kit, not necessarily between each other) but only when you know what the responses are for a given input. For example, my Hanna Alk reads about .2 higher than the standard always, my Red Sea Alk (until I adjusted what I consider a solid color change) was off by as much as .7 always. That's not to say that one is more accurate than the other, that's a marginal difference really, it's how we perform the test and read the results. So I can now use both Hanna and Red Sea with confidence but I now know how to correctly interpret each of their readings. The Hanna is nice because it does take out some our 'eye balling' but it's still going to have an error due limitations of the test.

Get some standards (several offered on BRS from specific element to overall seawater) and then you'll be able to have a lot more confidence in the results.

I was not aware that BRS offered testing standards for specific elements...I am aware of the Fauna Marin Multi Reference Standard...but not individual element standards...could you point me to them.

Thanks

Rick

 

[Quietman]

I was not aware that BRS offered testing standards for specific elements...I am aware of the Fauna Marin Multi Reference Standard...but not individual element standards...could you point me to them.

Thanks

Rick

Under Hanna...Cal standards for them. Some Aquaforest kits also have them included. And of course salinity.

 

[Rick Mathew]

Under Hanna...Cal standards for them. Some Aquaforest kits also have them included. And of course salinity.

Thanks.....Are you referring to the Hanna Calibration Check Sets for the Hanna individual Checkers?

 

[PatW]

Here is my take:

ALK. I have used Hanna and Red Sea. Hanna is pretty user independent. Red Sea is based on interpretation of the end point color which for me varies more. I do get pretty close agreement with both tests though. I would go with the Hanna.

Phosphate: That is a high reading. You might give it a retest. I find my Hanna can give a sky high reading every now and then. I think it is caused by a little particle of nutrient rich stuff in the test vial. But for phosphate, Hanna is the best test.

Nitrate: You got that big of a difference? Well, I never liked API for nitrate. Salifert, if memory serves, is about guessing how pink the sample but I think that result would be by far the better one.

Calcium: For calcium, Hanna does not have a high rep. I use Red Sea Pro and I am not really high on the accuracy. I would think it would be plus or minus 10. So the two results agree in that your calcium is kinda high but safe.

 

[Quietman]

Thanks.....Are you referring to the Hanna Calibration Check Sets for the Hanna individual Checkers?

Yup. And I think I've read somewhere about creating your own standards, but can't find it now. I'm sure it's possible for some...whether it's worth it or safe I'll leave to a professional.

 

[Quietman]

Side note: I dug out my old API (not expired) nitrate test kit. It was very close (+/- 1 ppm) from Red Sea kit. I did API before I did Red Sea to try and eliminate confirmation bias (I think that's the right bias).

Anyhow...it is a bit harder to tell since there's a 5ppm range between colors, but not sure how much 1 or 2 ppm matter anyway when we're talking hobby kits. Decimals are for show I think in most cases.

Wondering now if API might be acceptable for what I need (not running ULNS). I'll run some more tests and post elsewhere later on. Just decided to try based on this post...so thanks @esther