Phosphates reading 0 per Hanna

Discussion in 'Water Chemistry' started by Billme, Jun 27, 2014.

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  1. Billme

    Billme Eyelash Blennie

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    My phosphate tests have been reading 0 for the past 4 weeks. The thing is, I don't believe it. I'm still showing some nitrates ( about 2.5), and I have done nothing too different lately. The cyano is there but not much. This also coincides with having picked up a couple boxes of new reagent. I went back to the LFS that I bought the reagent from and he tested a sample of my water and came up with the same thing. He also mentioned that surprisingly, his home aquarium came up with 0 phosphates. I also tested my wife's nano and came up with 0 phosphates. The nitrates in her tank are 10 and I haven't been changing the filters lately as much as I should. Her tank should be showing some phosphates. I using phosguard at about half the recommended dose. Just wondering if anyone else has used a newer hanna reagent and their thoughts on the results?
     
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  3. Alfie uk

    Alfie uk Feather Duster

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    I dont use them myself but I have read that different batches can give quite conflicting results..have you got a salifert or something to compare it to?
    I know you say there isn't much cyano but is it possible it could be absorbing the po4?
     
  4. Servillius

    Servillius Montipora Digitata

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    Hanna works fine and is consistent from batch to batch in my experience, but only if you do the test very correctly. I cut the reagent packet open before I start. I then get a two minute timer ready. Once I add the reagent, I start the time and gently agitate by turning the vial over then back for the full 2 minutes. I stop in the middle briefly to clean the vial. Only at the end of two minutes do you start the three minute timer.

    The problem is if you go a little over, the machine will shut off. You have to get the timing right then stick to the method rigorously. I used to get 0 all the time. I now get readings from 0.01 to 0.04 and when the nutrients were worse, I would get readings around 0.07 to 0.09. I've sent samples to a lab twice for analysis and both times Hanna matched really well.
     
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  5. Kevin_E

    Kevin_E Giant Squid

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    Do you use the ULR?
     
  6. Billme

    Billme Eyelash Blennie

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    Only at the end of two minutes do you start the three minute timer.

    Thanks for the pointers servillus. SDI to understand, between mixing and waiting, it's 5 minutes?
     
  7. Billme

    Billme Eyelash Blennie

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    Not sure what the ulr is. It's the standard optical Hanna.
     
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  9. Billme

    Billme Eyelash Blennie

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    Good point Alfie. I'll pick up a salifert kit.
     
  10. Kevin_E

    Kevin_E Giant Squid

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    Ultra low resolution. Should say ULR on it. It reads in parts per billion instead on ppm. It reads much lower concentrations.
     
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  11. Servillius

    Servillius Montipora Digitata

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    Yep, between mixing and waiting it's roughly 5 minutes. I don't use the ULR. Just the standard model.
     
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  12. Kevin_E

    Kevin_E Giant Squid

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    That may be why you're getting zero.
     
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