Phosphate test levels

Discussion in 'Reef Chemistry' started by Nav, Apr 13, 2015.

  1. Nav

    Nav Director of Marketing & Photography

    Recently I used HI713 reagent (from @jonmos75) to compare phosphate levels (same water) on both HI713 & HI93713 meters and results were identical (0.04)

    This week I purchased 100 HI93713 reagents and tested in the HI93713 meter and the phos was 0.06. Just to be sure I used a remaining HI713 reagent in my HI93713 meter to compare and the phos was 0.03.

    Hanna claims the reagents can be swapped. For me the same reagent in different meters read the same and now different reagents in the same meter read different.

    Should I trust the HI93713 reagent in the HI93713 meter or the HI713 reagent in the HI93713 meter?
     
  2. jonmos75

    jonmos75 Supporting Member

    No expert here....but the HI93713 is a phosphate reagent and what I gave you (HI713) was a phosphorus reagent....so I am sure there could be a slight variation???....on the internet I was informed that the Ultra Low Phosphorus was a little bit better in getting the closest measurement yet that is up to speculation... (remember to do the math conversion with the HI713 reagent), but the issues I have had is with the Hanna Test Checkers is you can do the same test back to back and get a little variance depending on placement of the vile from the different test step, fingerprints on the vile, and also how long you wait between shaking the vile for two minutes to when putting it in the tester....(example I always put the 10mL label facing one way during all the tests, I also use a microfiber cloth and wipe off all fingerprints during the testing steps.)

    I talked to Hanna tech and they said you have to follow the instructions to the letter if you waste any time between the mixing the reagent and putting in the tester...

    One time I did an experiment and took one vile of non-reagent saltwater and one vile of the reagent mixed with saltwater and I repeated the step every 5 min for 20 min and got a different results each time which confirmed what Hanna tech said....
     
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  3. Enderturtle

    Enderturtle Volunteer

    Theres also a level of precision with each test kit/machine.

    I also do what jonmos says. If you want to try and see consistent results with a test kits your methods for getting those results must also be consistent. Youre only testing like 10mL of water so any small differences are noticible. I shakethe reagent hard to mix up the reagent even though it says not to shake hard. Not sure if thats right.

    I think the hanna low range phosphate green egg tester has a precision of +/- 0.1? Not sure about your other test kit.

    I wouldnt worry too much about that difference. Stick with your usual routine for maintaining your tank parameters. And watch for overfeeding/things dying (snails etc).
     
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  4. Nav

    Nav Director of Marketing & Photography

    Jon, I do exactly the steps u mentioned, time it, get rid of fingerprints, etc. Also rinse in RO-DI when done. One thing I need to know is how you dry it? Do you stuff a facial or kitchen tissue inside the vial and wipe or just let it sit upside-down and dry? What I noticed are after its dried, the next time when I add the 10ml water and shake, i see super-fine dust that I assume is from the tissue paper...

    Do you do anything on the device in terms of maintenance? I have no idea whats inside but should something be wiped or cleaned once in a while? my device is like several years old ;)

    I agree with the Phosphorous vs Phosphate... I'm not sure how using your reagent on both our different devices gave same results earlier. See this listing on ebay too mentioning the reagents are identical

    http://www.ebay.com/itm/25x-HANNA-H...868?pt=LH_DefaultDomain_0&hash=item563afb5f1c
     
  5. jonmos75

    jonmos75 Supporting Member

    I actually store my vile full of RO/DI water and then dump it out rinse with tank water and dump it out and then do my test, rinse with RO/DI and then store them full of RO/DI water until next time.

    I don't do anything to clean the device except try to keep the lid closed so less particles don't get in the tester

    Not sure, but a call to Hanna would be a way to confirm that....I also order all my Test kits from The Test Equipment Depot
     
  6. Coral reefer

    Coral reefer President

    Once again, you are over thinking it. The difference in those readings is basically nothing, and well within the accuracy of the tester.
     
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  7. bluprntguy

    bluprntguy Webmaster

    The reagents are identical for these two machines because the machines are basically identical, except for the fact that they spit the numbers back in a different format.

    There are going to be minor differences with the batches of reagents, whichever one you buy. The margin of error of the machine is 4% or .04, whichever is greater. All your tests are "the same" when you factor in the margin of error for these machines. There is no real difference between a reading of .04, .03 or .06.
     
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  8. Nav

    Nav Director of Marketing & Photography

    Jon, never thought about storing with RO/DI. Thanks!

    Mike, agreed. This is just my second test on this meter and I want to make sure I'm doing it right.

    Thx for the inputs Philip.
     
  9. neuro

    neuro Webmaster

    Nav,

    I agree with all of the inputs, but have you tried doing the same test more than once with the same vial?
    I do at least two or three tests, and average the results.
     
  10. jonmos75

    jonmos75 Supporting Member

    I normally will test with Red Sea Test kits and use the Hanna to confirm and if it way off I will re-run the tests...
     
  11. Nav

    Nav Director of Marketing & Photography

    Alfred, 2 or 3 reagents or just re-run the same mixed vial couple of times? I haven't tried either and will do that next time.

    I've also heard of people doing it 2 different ways.
    1) First vial with clean water and other with mixed reagent, 0 the first one and sample the second vial with reagent.
    2) Use one vial, 0 it first, then mix reagent and sample it.

    I've done 2, and I hope thats the right way?
     
  12. jonmos75

    jonmos75 Supporting Member

    Nav,

    You can't run the same test multiple times as I described on post #2 you will get different results as the time is going by...so you will have to start over with your tests...

    As far as people using two vials the problem with that is glass has imperfections in it and how light goes threw the vials so you can get inconstancy between the two different vials so that is why I do option two one vile get its base reading and add the reagent and finish the test...
     
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  13. neuro

    neuro Webmaster

    Don't use new reagents, just use the same two vials you have, just re-run the test again. Ie don't mix a new batch each time.

    I perform #1 kinda. The second vial is included so that you can have the tank water mixed with reagent already. I just do the test with two vials of tank water, one with no regeant, and one with. That's it.

    If you perform #2, and if you are unable to fully mix the reagent within an allotted time, it will reset itself--This has happened to me.

    So I mix the second vial until I can't see the reagent anymore and then start the test with both vials.

    Here is a video from hannah that demonstrates how to add the reagent to get the full amount out without a problem:
     
  14. Nav

    Nav Director of Marketing & Photography

    Most videos I see, they do it in the same vial, but I know many that do #1.

    Next time i test, I'll start with #1, then in the unmixed vial use new reagent and do #2. Will compare and make sure they're the same :)
     
  15. jonmos75

    jonmos75 Supporting Member

    Wow....I am surprised you don't get different results....as I did when I was experimenting with that concept....

    I have never had an issue of not getting the reagent to mix (completely dissolved) in the two minute shake time...but unlike Mike @Enderturtle I don't shake fast and hard as it created too many micro bubbles in the vile during the 3min test time, but also saying this Mike is absolutely correct in as long as you do the same test procedures then your test results should be fairly accurate....
     
  16. neuro

    neuro Webmaster

    wait, can you clarify which concept that you're surprised I don't get different results? I always get different results, but they rarely vary more than a hundredth of a unit.
     
  17. jonmos75

    jonmos75 Supporting Member

    When I first got my test kit I used one vial of 10mL of saltwater as the base and then used another vial with saltwater and reagent and went threw the test procedure and got my result and then cleared the meter and started the test again with one saltwater vile and the same saltwater/reagent vial and did this test 4 or 5 times back and my results were changing in each test so I called Hanna and talked to one of there support reps and he told me that by doing the test over & over again the amount of time the reagent is mixed in the vials it will change what the meter will read and give different results.......that is when he advised me to only use one vile at a time and to place the vile in the same direction each time I test...that is why I use the 10mL icon to know that I always face it towards the front...

    How I do the test:
    1) Cut the reagent package in a "V" for easy poring like this video
    2) I will fill saltwater in a vile to the bottom of the meniscus to the 10mL line
    3) Wipe all fingerprints off with a microfiber cloth
    4) Touching only the cap I insert the vial into the meter with the "10mL" logo facing the front
    5) I then after it has read the saltwater I remove the vile by the cap and wrap the vial with my microfiber cloth and remove the cap deposit the reagent as shown in the video and reinstall the cap and the I put my thumb on the bottom of the vile and my pointer finger on the cap a do a medium to slow rock back and forth for two minute.
    6) Insert vial by the cap back and make sure that the "10mL" logo is facing the front into the meter and hold the button until it has the 3min counter pull up and then the results
     
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  18. neuro

    neuro Webmaster

    thanks for the clarification!

    @Nav - disregard what I said then.

    @jonmos75 - you know, I could have sworn I read somewhere in either the manual or online, that mentioned the use of both cuvettes. I do have a super old checker, maybe I read it incorrectly somewhere.

    Though, that begs the question: If both samples are of the same water, why would it matter?

    EDIT: nevermind. the issue is that both cuvettes could be different. Buying two identical cuvettes is more expensive than buying two cuvettes:

    http://www.reefcentral.com/forums/showthread.php?p=20131840#post20131840
     
  19. jonmos75

    jonmos75 Supporting Member

    @neuro - I think there intention was to use both cuvettes...or least to give the customer that option, yet they found just using one created better results
     
    neuro likes this.
  20. Coral reefer

    Coral reefer President

    It works w two, but yeah, not as good. I do it on occasion if I mess up and take too long or something.
     
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