help with Hanna phosphate checker
 

so i have a hanna checker and i get different readings with the same test sample each time, now i know there is a time limit on how long the test sample will be accurate for, but im doing all the readings all within 6-9min of adding the additive. when i do my first reading i get .17 and the next two i get .10, im just wondering if any of you use a hanna checker and what is the most accurate way of using it

I always get the little package open and ready to add to the testing sample bottle for C-2 test before I start the test procedure, you have max 3 mins. to dissolve the powder for C-2 test and make sure you have a dry soft rag on hand to polish off all the finger prints on the test bottle before you put it in the checker for both C-1 & C-2 testing.
Hope this helps.

Ive always had the same problem with the hanna regardless of wiping down the glass tubes or not. I havent used it because of this for quite awhile. Interested to hear what others say.

EDIT - 3 mins max? Hm that could have played a part, I dont remember if i was that fast or not.

And for C2:, be sure to hold the button until the 3 min timer appears. My results don't vary at all, usually the same or .01. That is if I do it right... As mentioned, have to get all the powder in cleanly, and needs to mix clear. And no fingerprints. Takes a little practice to get your routine dialed. But after that, very easy, actually.

I find the challenge is to get all the regent into the sample vial. Any tips?

I cut the top off and bend the middle of the package into a v type funnel and tap it in , also makes me feel like a scientist

Cut the packet, and shape a funnel on the side. Hold the vial at an angle, not straight up and down. Then gently tap the back of the packet with your finger. And be sure the insides of the packet are opened, too, so the powder doesn't get stuck coming out.

And I think someone said it before but clean the vials off with a cloth the finger prints or salt water on the outside will give you a false high

It could be that the reagent powder isn't completely dissolved for your first reading. It takes me a few minuted to get all the floaties dissolved...

Either way, in the grand scheme of things, the difference between 0.10 and 0.17 isn't the end of the world. Or is it?

well im trying to get my water to .05, i have also read that you shouldn't have any air bubble in the vile.

3min seems to be a bit much it terms of the sample diluting, it takes at least that long to get it to dissolve

Get a small piece of wax paper and pour the regent onto it then into the vial , its too hard to get it all out of the package any other way . I add it to the vial then shake for a minute to a minute and a half max . I also make sure to clean the vials right after use with ro water . I get quite consistant readings this way.

I think thats a good tip with the wax paper, Im going to try that because its so hard to get it all from packet and not spill some. And 2X on washing with RO water, also a little drying stand works great. Think wine decanter drying stand...

i cut the top off and then tear one side all the way open so I can spread the packet more. then i do the tap and i can get very close to all of it into the vial. it's still quite a pain tho i'm going to try the wax paper idea.

I know, but the difference between 0.10 and 0.17 puts it in the same ballpark. It's not an order of magnitude difference.

Where did the 3 minute rule come from? It takes me longer than 3 minutes to dissolve all the reagent floaties.

The meter shuts off automatically after three minutes. Convenient huh?

I know, but you can pre-mix your vial before you even turn the meter on. That's what I do....

they give you two vials. if they were both equally clean you could in theory zero the meter with the first and already have the second mixed with the reagent. but i'm wondering if the vials being different could mess with the result.

The difference in clarity between the two vials is enough to throw your reading off.

if that's the case and we can't assume that two seemingly identical vials are the same to the meter then perhaps even inserting the same vial back into it but rotating it differently could be a factor too.

Bingo... Which is why the Hanna colorimeters for phosphate get such bad reviews. They are a pretty flawed method if two different vials, etc. interfere with the reliable results. And having an auto-off of three minutes when simply mixing the reagent takes a minimum of two was just poor planning...

you can compare the vials by doing a "test" using each with ro, no reagent. I've ran it a couple of times, different order and always get zero.

I always use a tissue to grab the vial. Finger prints are enough to throw the whole reading away. Alongside, one tiny floating particle in the vial is also enough to give you false reading. And the worst part is the 3 min shut down time. I don't know what the people at hanna was thinking? I guess according to them, its "cost effective" to throw away a dissolved solution than to change a battery for adding an extra minute to the shut off time, not to mention the dedication to pour the powder in and the two minutes shaking time. I really hate this photometer from the bottom of my heart but well, if I get everything 100% right, I know I am going to get a much more reliable reading than any other test kits. But reaching the 100% takes a lot of work and luck too.

so you zero with one vial and have the other mixed?

why else would they give us two lol?

Geez guys, it is really not that hard... I only use one vial, and always get it completely mixed every time. Like I said, just have to do it right as described above, and it is then very accurate and consistent.

+1

my readings sometimes vary so it's good conversation to me. if there's ways to make the process more accurate it's worth discussing.

when I started and was slow with the Hanna was using both vials. Now do the C1, add reagent, shake, hold the button to get the 3 minute timer started then done. Seen a video where you crease the packet to get a funnel helps to pour.

i wish hanna would sell a little canister with spoon similar to what elos does.

I wish they'd just increase the automatic off time to five or ten minutes. I also wish they'd use a method that isn't so finicky to tiny variables and would be more consistent.

Having said that the phosphorous ULR checker does seem to be pretty reliable for me. It uses the same process as the phosphate but measures phosphorous; then you do some simple math to estimate your phosphate concentrations.

Maybe I'm slow, but I cannot fill vial, add ALL the reagent in the pouch, and completely mix it in 3 min. At the end of 3 min I still have solid particles of reagent swirling in the vial. I don't want to measure it unless it's completely dissolved. That's why I use 2 vials.

What do you mean fill the vial?? That is done at the beginning before C1. I also have the packet cut, funnel formed and ready to pour before the 3 min time limit begins. I usually use close to the full 3 min before pressing (and holding) C2, but have no trouble completely dissolving the powder.

Yeah I'm not sure if you're doing it right if you are rushing to fill the vial in a certain amount of time.

1. Fill the vial , and wipe the outside to remove finger prints.

2. Turn on meter

3. When it reads C1 add the vial to the meter and press the button.

4. When it reads C2 remove the vial from the meter and dump in the powder , give it a good shake till everything is dissolved and then wipe the vial for fingerprints. Put the vial back into the meter and HOLD the button down till the 3 minute timer starts. (Step 4 must be done within 3 minutes)

As others have said , tear open the reagent prior to step 1 ,so that its all ready to go , I personally cut off 3 sides so it opens up like a butterfly so I can get all the powder in , but the wax paper idea sounds like a great choice as well.

Also do not forget to keep an eye on the 3 minute timer , because after it counts down and shows the reading , it shuts the meter off within about 5 seconds.