PO4 test kits - Hanna VS Salifert

[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]

Originally Posted by 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.

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

Originally Posted by GoFish

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!!!!

[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!'

[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]

Originally Posted by gregzz4

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.

Originally Posted by 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?

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.

[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.