Test kit conflicts - Hanna vs Red Sea

[merkmerk73]

I've always struggled with the Red Sea Phosphate kit, but I'm also having big discrepancies with Hanna readings on Nitrates

Red Sea phosphate has been telling me I'm around .12 - having been around .03-.08 for months and months before that. Okay fine.

Hanna says my phosphates are .28 across two tests.

Red Sea nitrates says I'm somewhere between 20 and 50 - let's say 35

Hanna says I'm at 14.1

Who do I trust?

Red sea seems all over the place on other kits too - their standard alkalinity and alkalinity pro kits read differently as well.

(for what it's worth I'm doing ~23% water changes daily until I can bring these levels down.)

 

[jda]

You just have to pick something. Have that be your standard.

For me, it is Salifert for Calcium and Alk and Hannah ULR for phosphorous. That is about all that I test, although I do have other test kits that I use from time to time.

If you are using Hannah colorimeter, then I would trust those if you are good at using them and the vials are really clean and stuff. Nitrate and phosphate test kits where you have to compare the color to a chart are really hard to determine unless they are just mostly clear.

Red Sea titration kits are decent when I used them. I just use Salifert since they have never let me down and are cheap and available.

In the end, just decide on which one you are going to put your faith in and stick with it.

 

[Doctorgori]

FWIW I don’t have a lot of confidence in my Hanna nitrate checker…
Following for other opinions on this checker in particular

 

[merkmerk73]

FWIW I don’t have a lot of confidence in my Hanna nitrate checker…
Following for other opinions on this checker in particular

It seems sus to me as well.

My red sea nitrates have been pretty consistently climbing so I'm used to seeing hardly any pink vs a good amount of pink to "uh oh" pink approaching 50 ppm

So when Hanna comes in and says "nah, 14" I am finding it hard to believe.

I also find the various types confusing - low range vs ultra low range vs high range...not sure when I'm supposed to use which.

 

[Doctorgori]

It seems sus to me as well.

My red sea nitrates have been pretty consistently climbing so I'm used to seeing hardly any pink vs a good amount of pink to "uh oh" pink approaching 50 ppm

So when Hanna comes in and says "nah, 14" I am finding it hard to believe.

I also find the various types confusing - low range vs ultra low range vs high range...not sure when I'm supposed to use which.

I think I’m probably “Safe” saying Hanna’s ULR Phosphate is pretty popular/trusted as is their Alkalinity Checker (most use the DKH version… The other “low range” phosphate check is no longer popular or practical (essentially)

You can trust Salifert for most test and I have used Nyos Nitrate and liked it

I can also safely say avoid Hanna Calcium, its goofy, and unreliable….I’m starting to think about throwing their Copper and Nitrate in the trash also

 

[RelaxingWithTheReef]

I've always struggled with the Red Sea Phosphate kit, but I'm also having big discrepancies with Hanna readings on Nitrates

Red Sea phosphate has been telling me I'm around .12 - having been around .03-.08 for months and months before that. Okay fine.

Hanna says my phosphates are .28 across two tests.

Red Sea nitrates says I'm somewhere between 20 and 50 - let's say 35

Hanna says I'm at 14.1

Who do I trust?

Red sea seems all over the place on other kits too - their standard alkalinity and alkalinity pro kits read differently as well.

(for what it's worth I'm doing ~23% water changes daily until I can bring these levels down.)

All of these kits are very frustrating to deal with.

Overall I consider the Red Sea Phosphate test pretty good, but there are a couple significant limitation users need to be aware of.

First the good news. At low phosphate levels the RedSea test reagents produce significantly more color contrast than Hanna’s best ULR testers, and this results in a more sensitive, accurate, and consistent result. The Hanna Phosphate ULR stated accuracy is a disappointing +-0.020 ppm plus an additional +-5% of the reading that speaks for itself.

But the RedSea test has a serious Achilles heel. The test saturates around 0.120 ppm. This means that any concentration over 0.120 ppm, will only read approximately 0.120 ppm. I believe this is the situation you were dealing with. When the test results are over 0.100 ppm, the RedSea results have to be discarded!

RedSea has a procedure in their instructions to dilute the sample to increase the range, and they recommend DI water. But the DI water should be tested by itself to verify it’s free of phosphate. My city water comes into the house at 0.500 – 1.000 ppm phosphate, so the DI system must be working properly to result in phosphate free water product water. You can also try bottled distilled water if the DI is a problem. Personally, I do not like the dilution process, and if the phosphate reads over 0.100 ppm, I believe the Hanna ULR test is the way to go.

The problem with Hanna is at levels below 0.050 ppm or so, no matter how careful I am, the results are typically not very consistent and repeatable. The Hanna test also seems very sensitive to contamination inside the cuvette. Good cleaning and rinsing with test water several times is required for good results. This also applies to the RedSea test.

The second RedSea issue I’ve found is with the reagents. I once received a kit where the results were always zero. Something was wrong with the reagents. I purchased the kit online, and it’s possible the kit was tampered with. If I’m not sure the kit is working properly, I will spike the 17 ml test sample with “Hach 256949 Phosphate Standard Solution 1 mg/L as phosphate.” Adding 0.17 ml will raise the phosphate approximately 0.010 ppm, and 0.34 ml will raise the phosphate approximately 0.020 ppm. If the test picks this up properly, I know its working.

 

[OPL]

With the exception of the Hanna HR and phosphorus ULR, all my test kits are Salifert. I’ve used Red Sea kits in the past but prefer Salifert.

I’ve found the Hanna kits to be quite accurate/reliable, I do an ICP every 4-6 weeks (sampled when I do a weekly test) and the results have been similar each time.