PO4 test kits - Hanna VS Salifert

[gregzz4]

Originally Posted by Ryanerickson

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]

Originally Posted by 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 .

Mhmm
I'm sure Hanna has a reason for the 3 minutes, but who am I to question it?
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

[Myka]

Originally Posted by 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 .

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.

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

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

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.