PO4 test kits - Hanna VS Salifert

[GoFish]

Just picked up a new Hanna ULR Phosphorus kit and tested tank. It says 72, so after some math (72 x 3.066 / 1000 = 0.221)
Then tested with Salifert kit and as always it shows only a slight hint of blue. Somewhere in the range of 0.00 - 0.03.
But based on what the Hanna ULR shows the Salifert kit should be showing a really blue test result.

Using only Salifert for the last couple years I've always had consistent test results.

Just did some major water changes to a new salt brand over the last week and tested last night with Hanna only and its down to .23 ppb (0.07 ppm). Haven't cross checked this with Salifert yet but assuming that will still show low

What should I trust more, Hanna or Salifert?

[Craigdillman]

Hanna is much much more accurate, it uses digital "eye" to read to color and doesnt rely on you "guessing" what shade of light blue the color is

Also the hanna ULR mesures in ppb then you convert it to ppm ,

[GoFish]

Makes sense. Just wondering why the Hanna says .221 ppm at the same time the Salifert has barely even a hint of blue in the range of 0.00-0.03 where it's should be showing a darker colour. I'm not a fan of the colour guessing game with Salifert but positive the shade is no darker than 0.03, let alone in the .1 - .25 range

I'll carry on using the ULR, I just thought the 2 were similar in accuracy

[Myka]

Could you describe in detail how you performed the test? I would expect the tests to read closer, and suspect you're doing something "off".

[GoFish]

Which test do you want the details of? I do something different than the directions say on both, the Salifert I stir the sample after adding the powder instead of swirling using the opposite end of the spoon that's rinsed (tap water) and dried very well with a new piece of paper towel. I read it using white light after 2-3 mins, either outside light if it's day time or a white fluorescent light in the living room.

And with the Hanna I don't shake it for 2 minutes, instead for 1 minute until the powder is dissolved and then hold the button for the 3 minute timer. I make sure there's no air bubbles inside the vial and keep the vial facing the same direction (10ml facing forward) for both the calibration and test, then rinse the vial with RO (using a syringe that's only ever used for this purpose) and leave the cap off when put back in the case to let it dry for next time. I found with the standard PO4 Hanna checker I used to have that if I shook the sample for 2 minutes the checker would turn off, not sure if the current versions still have this 2 min/off feature

[Delphinus]

If you get consistent readings with the Hanna checker using the 3 minute timer as you describe then I'd feel fairly confident in its numbers. Assuming of course you have newish reagents - if memory serves there was a time period that there were bad batches of reagents (fairly easy to confirm if you had one of the bad batches - just do 2 tests in a row and see if the #'s match well enough or not).

Not sure how this applies to Salifert's PO4 test kit but I noticed that with the Mg test kit (which is a titration based test kit rather than a colour comparison, so this might be an apples-to-oranges comparison) that the reagents would expire and then you wouldn't get good readings anymore. So if the test kit is more than say a year old, I'd consider replacing it.

If in doubt though, I think repeatability is the real pathway to figuring out which is the more trustworthy result, if you know someone who has a third test kit that you could ask for a test, see if you can get a value that corroborates one for you over the other..

[GoFish]

Well this is slightly embarrassing. I just checked the Salifert PO4 kit and it expired in 08.16... could swear I checked all 4 boxes before Boxing Day And they were all good from 2018-2020 but for some reason had 2 Alk kits together and the PO4 was on a different shelf

Anyway, pointless technical thread question with an expired kit :redface:

However I may have an isssue...
Just did 2 back to back tests with the Hanna and got 125ppb (.38ppm) and then 114ppb (.35ppm). Might be more inaccurate than it's suppose to be. Instructions say within ±5 ppb ±5% of reading. It was 23ppb (.07) last night! Will need to do some research into this. The Salifert still shows much lower (but it's expired, interesting to know anyways)

[Myka]

And with the Hanna I don't shake it for 2 minutes, instead for 1 minute until the powder is dissolved and then hold the button for the 3 minute timer. I make sure there's no air bubbles inside the vial and keep the vial facing the same direction (10ml facing forward) for both the calibration and test, then rinse the vial with RO (using a syringe that's only ever used for this purpose) and leave the cap off when put back in the case to let it dry for next time. I found with the standard PO4 Hanna checker I used to have that if I shook the sample for 2 minutes the checker would turn off, not sure if the current versions still have this 2 min/off feature

The ULR checker needs to be mixed for 2 minutes before starting the 3 minute countdown. It needs 5 minutes of development. The checker allows for this. I'd also suggest you do not shake the vial, but tilt it back and forth to mix because microbubbles in the vial will mess up the readings, so will fingerprints or water marks on the outside of the vial. Dried tap water inside the vial from your last rinse will often give you false high readings too.

Here's a very detailed description of how I perform the test:

I use a syringe to fill the vial with a couple mL of tank water, shake vigorously, then empty it and shake as much water out as possible. If there are drops left near the top of the vial I will use a bit of paper towel to get them. Then I add tank water to the 10 mL mark (bottom of the water's curve), cap it. I get the reagent packet ready (so it's quicker) by flicking all the powder down into one corner, then cut off two sides, and squish it open. I clean the outside of the vial with a microfiber cloth. Then I turn on the checker, wait for "C1". Insert the vial with the "10" on the vial lined up with a mark I put on the top of the checker, close lid, set the checker down. Hit the button. Wait for "C2". Add the reagent packet, cap the vial and gently tilt it side to side for 2 mins (I time it). Hold down the button on the checker until it starts the 3 min countdown. When there's about 1 min left, I turn the vial a few times, make sure there are no air bubble on the vial sides, clean the vial with the microfiber cloth again, and insert the vial into the checker, close the lid and wait for the reading (there's about 45 seconds remaining when I insert the vial). Once I get a reading I immediately take the vial to the sink and rinse it repeatedly with water that is as hot as I can stand, using my thumb to seal water inside it and shaking it vigorously. I also rinse the lid. Afterwards I rinse it in RO/DI water, and shake it out vigorously.

[Potatohead]

The Hanna checker works and it is accurate, however you need to be very, very diligent about test procedure and the vials need to be spotless.

What I do is;

- Cut open one of the reagent packs and make sure there is none stuck in the corners, etc. Fold so one long edge goes into a V shape.
- Turn on checker, fill vial with tank water. Wipe with a cotton towel to dry, then a microfibre towel to remove streaks/debris. When very clean, put in checker.
- When C2 comes I pull the vial, carefully put in reagent, shake (gently) for a 100 count. Re-do the towel thing, shake a few more times to get any bubbles stuck on the vial to rise to the top, then put it back in the checker for three minute countdown. Keep in mind to do all this you only have three minutes or the checker will power off.

After reading Myka's post, seems pretty similar.

I have had my complaints of this checker in the past, but since using this method and making sure the vials are spotless, it has been very consistent.

[GoFish]

Well may need to work in my precision testing skills just a touch. I learned from having the calcium checker that these things can be super finicky. I was never able to get anywhere near consistent back to back readings with the calcium checker so ended up selling it and sticking with Salifert.

Forgot to mention I do a couple extra things mentioned in the last couple posts with some slight differences. The Hanna vials gets rinsed with tank water before use if I remember, but I feel this is a bit of a waste of time seeing as how they get rinsed with RODI before being put away. Definitely in between test if done at the same time to double check. I also make sure there are no finger prints by giving it a good polish with the inside of my t-shirt usually and check for fibres on the outside. I give the vial a good shake for 1 minute until all crystals are dissolved, and yes it creates air bubbles, but to remedy this I spin the vial horizontally and allow the big bubble inside to dissipate the micro bubbles. If there's some micro bubbles stuck, it gets a tap on the counter and some more rolling. Until they're all gone.
And with the regent pack it gets shaken and flicked a bunch of times while holding one corner upwards, 2 sides cut along the dotted line and the open the flap by pressing inwards from the sides and at no point are there any fingers or anything touching the inside silver lining of the packet. Then a vee shape is formed, powder is dumped, pack is flicked until there no more powder left. Well there's a bit of powder residue left but that near impossible to remove. It's consistent anyway

Potatohead & Mindy: May put a microfibre towel with the checkers from now on, good idea.
Mindy: Not sure about drying the vial inside with paper towel before testing, i'd wonder about getting fibres left behind in the vial? Good call on leaving the vial out for the 3 minutes countdown to give it one more shake, will try this. Do you think rinsing it with hot water makes any difference? I just use cold usually

And at the end of the day I'm not expecting exact back to back numbers, the 8 percent difference last night is fine with me. Just trying to get in the low range to help combat tiny bits of algae that wil never completely go away. Would love to see anything below ten ppb right now, which is what the Salifert is always giving the result for...

[Myka]

Well may need to work in my precision testing skills just a touch. I learned from having the calcium checker that these things can be super finicky. I was never able to get anywhere near consistent back to back readings with the calcium checker so ended up selling it and sticking with Salifert.

The calcium checker is horrible. It's not your fault. That checker is NOT user friendly, and few people can report consistent, repeatable results. :lol:

Potatohead & Mindy: May put a microfibre towel with the checkers from now on, good idea.
Mindy: Not sure about drying the vial inside with paper towel before testing, i'd wonder about getting fibres left behind in the vial? Good call on leaving the vial out for the 3 minutes countdown to give it one more shake, will try this. Do you think rinsing it with hot water makes any difference? I just use cold usually

The hot water rinse and drying at the end is to remove any blue residue inside the vial since the blue color (which may or may not actually be visible to you) sticks to the vial, and over time will leave a "stain" that takes some serious scrubbing to remove, and because of the shape of the vial scrubbing is difficult. The tank water rinse at the beginning is to remove any fibers from the drying of the vial before storage. Since tap water could easily throw off the readings I use tank water. I doubt there are any fibers introduced when I clean the top of the vial curing the process as I'm really just putting it gently in the opening and the paper towel wicks any drops out, there isn't much movement of the paper towel.

[Delphinus]

Re. the Calcium checker - what, people have trouble retrieving only a single molecule of tank water? Who could have foreseen that!!!! :lol:

[gregzz4]

Meant to reply last week but got busy and forgot.

Mindy, have you performed back to back tests to see if your procedure gives you a different reading than the instructions' procedure would?
One test your way and one test the Hanna way?

I ask because you're supposed to;
Swirl or whatever for 2 minutes, then insert the cuvette and hold the button to start the 3 minute countdown.
I double-checked; their online video shows it this way.

What I gather is the full countdown allows any un-dissolved powder to settle before it takes the reading.

I use the regular model HI713 and find it's always been reliable by doing the above, even with back to back tests - ya know, for those times when it reads 'what the hell? It can't be that high!' :lol:

[Ryanerickson]

I tried mindys method it gets me way lower results, 4-6 ppb so almost none existent I'm also questioning if this method is correct as its not what the instruction say to do,
I also watched a video they did not use this method either.
How did you get this method for testing mindy?

[Myka]

Mindy, have you performed back to back tests to see if your procedure gives you a different reading than the instructions' procedure would?
One test your way and one test the Hanna way?

What I gather is the full countdown allows any un-dissolved powder to settle before it takes the reading.

I've never watched their videos - actually I didn't know they made any. I'm not sure what I'm doing differently from "the Hanna way"? Could you explain? The method I use is one that is very common with the "purists" (lol) on Reef Central and Reef2Reef, and supposedly the proper way to do it.

I never get undissolved powder, so I'm not sure what's up with that. However, the countdown is for color development.

I tried mindys method it gets me way lower results, 4-6 ppb so almost none existent I'm also questioning if this method is correct as its not what the instruction say to do,
I also watched a video they did not use this method either.
How did you get this method for testing mindy?

See above. :) What am I doing different?

[Ryanerickson]

Well in the instruction from what I understand you poor the powder into vial right after c2 is displayed when it's dissolved you add to unit and hold botton tell 3:00 countdown starts.

[Ryanerickson]

I prefer your method as its easier but what's right

[Myka]

Well in the instruction from what I understand you poor the powder into vial right after c2 is displayed when it's dissolved you add to unit and hold botton tell 3:00 countdown starts.

My instructions say to mix the cuvette for 2 minutes, then start the 3 min countdown.

[Ryanerickson]

Mine don't neither do any videos I've watched

http://i864.photobucket.com/albums/ab208/ryan_erickson/Screenshot_20170112-192525_zpspwjiqcvh.png

[Ryanerickson]

What I'm trying to say is they say to replace vial before 3 minute count down

[gregzz4]

What I'm trying to say is they say to replace vial before 3 minute count down
'xactly

No holding the cuvette outside the tester and 're-mix a bit more' before adding to the tester.

Mix, insert, hold button to start 3min timer

[Myka]

I don't think that makes a difference. I just do that to make sure all he bubbles are out. What difference would it make?

[Ryanerickson]

Difference for me was lower results with your method to me it looks like the powder mixes better with the longer time frame to work with it .

[gregzz4]

Difference for me was lower results with your method to me it looks like the powder mixes better with the longer time frame to work with it .
Mhmm
I'm sure Hanna has a reason for the 3 minutes, but who am I to question it? :mrgreen:
I think I'll stick with the Mfg methods
Sorry Mindy. I trust and love all your input/insight/knowledge - it's priceless. But in this case, nah :wink:

[Myka]

Difference for me was lower results with your method to me it looks like the powder mixes better with the longer time frame to work with it .
That doesn't make sense though. It's just powder, it's not engineered to only mix so much in 2 minutes. I never have unmixed powder after the 2 mins anyway. If I see the bubbles are all out, I'll often put it right into the checker after the 2 mins mixing. I've never had unexpected or unusual results. I'll give it a shot today.

[Myka]

Ok, I just ran the stupid checker 5 times. :lol:

Twice on my display, once your way, once my way. I got 0 ppb both times. That's useless. :lol:

Then I tried the fish QT tank...it's too high for the ULR. That's useless. :D

Then trying to figure out what I can do...hmm, maybe make some SW with tap water? Hmm... oh wait! I have a bin cycling some dry rock! So I test the bin twice, once my way, once your way.

Put the cuvette in the checker right after the 2 minute mix - 99 ppb
Continue to mix cuvette after the 2 min, and put in checker at 45 sec left on 3 min countdown - 103 ppb

So 4 ppb is within the accuracy and EMC deviation which is +/- 5 ppb (each!), so essentially, my readings are the same as I expected they would be.

[Ryanerickson]

I also did it both ways last night I got a ready of 12 the instruction way and 5 your way one thing I find doing this your way is I have much more time to Polish up the vial and confirm all micro bubbles are gone, possibly this is why I get the lower reading who knows.

[tang daddy]

Ryan is there still powder in your vial after the short time you mix?
I usually premix my vials then do the test. But maybe I'll try the other method this time. Reason I premix before starting the test is because the powder takes time to melt and mix in. Perhaps my water is not warm enough. I find that emptying the packet into the vial and mixing it 10times with a rolling motion leaves a bunch of unmixed powder at the bottom.

[Delphinus]

Maybe slightly off topic but being that I've been doing a lot of PO4 testing lately, I noticed something. I can tell when I'm about to get a wing nut reading, by when it looks like the colour didn't change at all rather than if it changes more than I expect. Ie. if I see a slight blue tinge to the water then I get a lower reading which tends to be inline with the day to day trend. But if it looks perfectly clear then I'll get a reading that puts me into the "WHOA WHAT HAPPENED IN THE TANK TODAY" territory. (Which of course I repeat the test and usually calm down when the next reading makes more sense).

I am using up a box of older reagents though, so maybe that's part of the issue in my case. I would say I get in the ballpark of 1 in 4, are these wingnut readings that don't make sense.