Hannah Phosphate Checker

[ddaddy2420]

I am beginning to doubt the reliability of this checker. Everytime I test for phosphates, I have to run 3 different tests and I still don't know which one is correct. What I have been doing is filling up a beaker of tank water and having a second beaker of tank water and the mixed reagent. The reason for this is after you shake the thing for 2 minutes and let it sit for a minute the checker turns off and I have to start all over again, so lately I have been keeping 2 beakers: one for tank water and one with tank water + reagent.

My first check yields: .11 phosphates
My second check which is done directly after the first one: .06
My third check of the same bottles done after the second: .01

so my results range from .11 to .01, testing the same bottles. Anyone else seeing this. The first problem is obviously having to use 2 test beakers but if I don't, I won't have enough time to run the test before it turns off. Besides the water is pulled from the tank at the same spot at the same time for the beakers so I don't see this as a huge issue. Still its not the standard way to test. But the range of phosphates is what is crazy. How can one sample go from a .11 to a .01? I think it has to do with settling time of the sample, which if thats the case they need to add that to the directions. And which is correct? I run gfo and carbon and matrix and chaeto, so my phosphates should be low. When i run AP phosphate, it shows I basically have none.

Anyone else have a similar issue with the hannah checkers?

 

[mcphock]

I have the same checker, and you definitely have enough time. Shake the vial very thoroughly, then invert the vial, changing the direction every time until the air in the vial has been exposed to all the sides.

Basically, you're using the tiny amount of air to clear off any remaining bubbles such that you can get an accurate reading. If you shake hard enough you'll dissolve the reagent and clear the bubbles with 30-45 seconds left. Dont forget to have the reagent packet already open so you can immediately dump it in after the two minutes start.

The 2 minute time sure is frustrating though. I wish it was a changeable setting.

 

[heathlindner25]

Imoa ,I don't like them, I found them to be very inconsistent

 

[cj22009]

If you do these steps the Hannah checker is reliable first make sure you get all the regent out of the packet and make sure it is dissolved 100% and make sure the glass tube is clean when you put it in to test

Sent from my DROID RAZR HD using Tapatalk 2

 

[ddaddy2420]

Trust me I have done all the steps exactly as the directions say. I wouldn't post here if i had not tried the steps given with the checker. From the sound of it, I am not the only one who has issues with them. Just asking here to see if anyone else had trouble with them or if it was just me.

 

[dr_ fish]

I personally don't believe the checkers are flawed at all. 99% of the time it comes out to be user error. The issue is that most people dont understand the theory behind how the checker works so they can eliminate as much human error as possible

There is a lot wrong with how you are performing the test in your first post.

You cannot use two different vials of water, you zeroed the photometer with a certain vial and water sample, you must use that same vial and water sample for the actual test. You should also get in the habit pf placing the vial in the checker with the same orientation every time. For example I always face the 10ml label forwards.

There is also plenty of time to shake the sample water before the checker times out, have the packet already open and ready before you begin. One mixed, shake the vial vigorously for 30-45 seconds and then invert the vial as many times as it takes in all directions to loosen the bubbles that will be stuck to the side of the vial.

And at all times the vial should be clean and without fingerprints or smudges. I usually clean the vial thoroughly before I zero the checker and then make sure I never touch the glass with my fingers afterwards.

Lastly, running back to back test with the same sample is going to give you different readings because of the half-life of the reaction going on inside the vial seems quick. I assume this is why the phosphate checker has a finite amount of time before it shuts off, to offer motivation for the person running the test to have the vial prepped in the appropriate amount of time for the checker to read the reaction at the correct time.