New Hanna phosphorus test reading 0

[avery155]

Hello everyone,

I just got a Hanna Phosphorus test kit, I ran the test twice and ended up with a reading of 0. The first time I followed the instructions however after shaking the vial for 2 minutes the meter had already shut off, so I got the other vial added tank water pressed the button, then swapped vials, 3 minutes later 0.

Ran test again 1 vial pre mixed all over, 1 vial tank water, same thing 0.

Nitrates are between 1-2 ppm from red Sea pro kit.

One is too light, 2 is too dark.

What gives?

[Bent]

There are two Hannah po4 meters, which one do you have?

[avery155]

Phosphorus ULR HI736

[RCS82]

I've been using my ULR736 for a couple years now and have never had a 0 reading. I do what you just did, use both vials and pre shake the one vial so its ready to go.
I think there was just another thread about the same 0 readings someone was getting. Regardless though it is tough to come to a concrete explanation. Your nitrates aren't real high, is it possible maybe your phosphates are that low?

[avery155]

I'm not sure if they can be that low. Feeding today about 4 hours ago consisted of a healthy portion of live black worms, immediately followed by some new life spectrum pellets.

Yesterday was a cube of PE mysis
day before was black worms and mysis.

I would think there should be some kind of reading unless it's getting used up?

[RCS82]

Maybe do another test to see if it's a zero again. If it is then mix up another vial with a little bit of the watery stuff from the PE mysis, definitely will be phosphates there.

[Bent]

I use the same meter.

The two vial method is inaccurate according to Hannah. The sample variance between the water in the control and the one in the reagent curvette will make the results incorrect. The control sample must be the same sample that the reagent is applied to.

Secondly, finger smudges and air bubbles will severely impact the results.

This is the proceedure I had to do to start getting accurate results.

Take an index card and fold it in half and unfold it so it is creased in the middle.

Open a packet of reagent and pour the reagent onto the index card. Make sure you get every last spec. Make sure you check the corners of the packet. You need all of it.

Turn the meter on

Fill the curvette with tank sample and cap. Shake and discard.

Fill the curvette again with sample to the line and cap

Take a microfiber cloth, hold the curvette by the cap and scrub the curvette very well with the microfiber cloth. Don’t touch the glass.

Put the curvette in the unit and make sure the lid snaps shut. The lid has to be closed completely. If the lid won’t stay closed gently rotate the curvette by turning it in the unit with the lid. Then try to shut the meter. Keep rotating and closing until the lid shuts.

When the meter says insert c2, take the curvette out of the meter, open the cap and dump the reagent into the curvette using the index card. Again make sure you get it all. Cap this curvette

Now, the directions say not to shake, but I cap it and shake the guts out of it. I shake it hard for a minute or so.

Now, hold the curvette horizontally and holding it by the cap turn it and use the microfiber cloth at the same time to wipe off your fingerprints.

Look at the curvette. There can be NO air bubbles on the sides of the curvette. If there are you can get rid of them by holding the curvette horizontally and rotating it.

Put the curvette in the meter, again making sure there are no air bubbles, no fingerprints and the lid closes completely.

Hold down the button until the timer starts to count down.

It seems like the three asinine things that really affect the reading are finger prints, air bubbles and the stupid lid to the meter not closing completely.

[BrettDS]

Originally Posted by Bent

Now, the directions say not to shake, but I cap it and shake the guts out of it. I shake it hard for a minute or so.

For what it’s worth, this is likely affecting your results to some degree. The directions say to “shake gently for two minutes”. Shaking hard may introduce more air into the sample and change it’s pH, which could affect the reading. Shaking for “a minute or so” may not give the color enough time to develop and could cause it to read slightly low, since they expect the mixing to continue for two full minutes.

The directions for the Hanna calcium checker do tell you to “shake vigorously” after adding that reagent, so if they really wanted you to shake vigorously they would tell you to do so.

Now, whether that makes a significant difference in the reading or not, I don’t know, but it does make sense to follow the directions as accurately as possible because they give you specific times and specific instructions for a reason.

As a side note, the other thing that I saw recently is that the thickness of the glass can vary slightly in different parts of the vial and orienting the vial differently for the calibration and the test can also affect the results. The tip I saw was to insure that the text that reads “10ml” on the vial always faces forward when you insert it. That way you can be sure that it is oriented the same way every time.

[RCS82]

Originally Posted by Bent

I use the same meter.

The two vial method is inaccurate according to Hannah. The sample variance between the water in the control and the one in the reagent curvette will make the results incorrect. The control sample must be the same sample that the reagent is applied to.

Aren't some people using RO or tap water for their first vial's water? I dip and shake both vials in the tank a couple times and then fill both. I find it hard to believe that one's water would be different than the other's. I do wish the ULR736 was like the Alk checker, so easy to add and mix the reagent in literally a few seconds. In any case I've never had any crazy readings from my checker that would cause me to really question it.

[BrettDS]

Originally Posted by RCS82

Aren't some people using RO or tap water for their first vial's water? I dip and shake both vials in the tank a couple times and then fill both. I find it hard to believe that one's water would be different than the other's. I do wish the ULR736 was like the Alk checker, so easy to add and mix the reagent in literally a few seconds. In any case I've never had any crazy readings from my checker that would cause me to really question it.

If someone does use RO or tap water for the first reading then they are not getting accurate readings. The point of the first reading is to calibrate the meter to the water you are going to test. Since it’s possible that your tank water may have a slight color to it, then by zeroing out the meter on a sample of tank water then it will be able to tell how much the color changes from the reagent. If you zero out the meter on perfectly clear RO water then any color that your tank water has will be interpreted as more color change and skew your readings.

As far as using two vials, the theory is that the vials aren’t perfect and one may be slightly thicker than the other (similar to what I mentioned above about different parts of each vial having slightly different thicknesses). A reading through slightly thicker glass will be different than a reading through slightly thinner glass. So the concern with using two vials isn’t that the water sample will be different between the two vials, but that the vials themselves might be slightly different.

All of these things are probably going to only make a very small difference and probably won’t affect the results significantly, but if you are striving to be as accurate as possible then you will want to use the same vial and orient it the same way for the calibration and the reading.

[Dsekula]

Originally Posted by RCS82

Aren't some people using RO or tap water for their first vial's water? I dip and shake both vials in the tank a couple times and then fill both. I find it hard to believe that one's water would be different than the other's. I do wish the ULR736 was like the Alk checker, so easy to add and mix the reagent in literally a few seconds. In any case I've never had any crazy readings from my checker that would cause me to really question it.

Before I start personally don't use the Hanna po4 kit (I use a lamotte 1200). Our business is considered a mobile labratory (we test water and wastewater water for federal compliance) here is our procedure for testing with a colorimiter in general.
Take one sample double the size of the sample cell (glass vile). Split between your sample and blank cells. Use one to zero out the meter and mix the other with reagents for testing. When mixing in reagents gently swirl in the reagent using a circular motion and holding the cap of the cell. Wipe off cell with microfiber before reading to ensure no fingerprints liquid or dust. For more sensitive tests silicone oil is used to clean the cell (a single drop) along with microfiber. Both cells need to be cleaned this way for an accurate reading btw most people forget to clean their blank

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[RCS82]

I get what you're putting down definitely, especially about the RO water being used to calibrate the first vial. I've never done that and never actually thought about doing that. I'll play around with only using 1 vial in the future as I see your point there. In the past though I have used up to 4 vials just to play around with different ways to test and still haven't seen any alarming results.

[Dsekula]

Originally Posted by RCS82

I get what you're putting down definitely, especially about the RO water being used to calibrate the first vial. I've never done that and never actually thought about doing that. I'll play around with only using 1 vial in the future as I see your point there. In the past though I have used up to 4 vials just to play around with different ways to test and still haven't seen any alarming results.

Keeping in mind these tests are looking for a change in color there may or may not be a different result in testing one two or four, all other factors being equal it would depend on how close the clarity of the sample tested is compaired to the one used to zero out the colorimiter.
The issue we see most that skewed results is when cells haven't been cleaned regularly. When this happens the reagents tint the glass causing a false result. So if the blank is tinted a false zero could occur and if the test is tinted a false result.

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[BrettDS]

Originally Posted by RCS82

I get what you're putting down definitely, especially about the RO water being used to calibrate the first vial. I've never done that and never actually thought about doing that. I'll play around with only using 1 vial in the future as I see your point there. In the past though I have used up to 4 vials just to play around with different ways to test and still haven't seen any alarming results.

Yeah, I suspect that glass thickness makes a pretty small difference really and I wonder if it would even be measurable with the Hanna checker, but at the same time it’s not too much trouble to use a single vial and make sure it’s always oriented the same way. It’s interesting to note that at dsekula’s lab they use two separate vials.

[Dsekula]

Originally Posted by BrettDS

Yeah, I suspect that glass thickness makes a pretty small difference really and I wonder if it would even be measurable with the Hanna checker, but at the same time it’s not too much trouble to use a single vial and make sure it’s always oriented the same way. It’s interesting to note that at dsekula’s lab they use two separate vials.

Most tests we do there isn't an option to use one cell. You folks are speaking of one specific test with one reagent. I'm talking about all water testing where many tests have multiple steps and consume time to prepare samples (test units time out at times too, then what would you do). Usually we're drawing one large sample and testing 5-50 different parameters. We prepare one blank and use it 5-50 times Since the entire draw is one sample, the sample is also in a static mixer to ensure uniformity for this process. So this isn't apples to apples I understand. Just figured it was worth sharing the process that is recognize as accurate to the feds . If it was feasible to use one cell for each test that could certainly lend uniformity to the result but in our experience if cells are kept in good repair the result won't suffer from using two.

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[RCS82]

That was great of you to share that and see how it relates on the hobby level. Very cool.
Back to the OP, and zero reading from the hanna checker. Is the whole kit new? The checker, vials and reagents or is it just new reagents? Could the reagents be from a bad lot? Maybe a fellow reefer or a lfs could let you try a different reagent from a different lot or batch.

[BrettDS]

Hanna does make standards to check your checkers as well. BRS sells the phosphorus one for like $14...

https://www.bulkreefsupply.com/hi736...standards.html

Edited to add that in looking at that it looks like it just comes with two vials... one clear and one pre colored. So it won’t verify the reagent, just the checker.

[Dealseer]

Originally Posted by Bent

There are two Hannah po4 meters, which one do you have?

There’s only one Hanna phosphorus meter.

[Dsekula]

Originally Posted by RCS82

That was great of you to share that and see how it relates on the hobby level. Very cool.
Back to the OP, and zero reading from the hanna checker. Is the whole kit new? The checker, vials and reagents or is it just new reagents? Could the reagents be from a bad lot? Maybe a fellow reefer or a lfs could let you try a different reagent from a different lot or batch.

You could also try two tests with different viles and compair results? The biggest issue we have is dirty or scratched viles giving false results. If you don't have another set you could attempt a split sample with the one vile method twice. I'd also get a second source to verify results on another test kit or method. If you don't have a friend close by a lfs or lab could help, most lfs will do a free test and this single test is usually a small fee from a lab.

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[Dsekula]

Originally Posted by Dsekula

You could also try two tests with different viles and compair results? The biggest issue we have is dirty or scratched viles giving false results. If you don't have another set you could attempt a split sample with the one vile method twice. I'd also get a second source to verify results on another test kit or method. If you don't have a friend close by a lfs or lab could help, most lfs will do a free test and this single test is usually a small fee from a lab.

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Something to also note, the company that makes these units Hanna or any company working the same way has to have a lab to ensure the equipment isn't faulty. Contacting them to discuss your results couldn't hurt. If it's a new kit they may even send a set of standards, viles, or reagents to you for little or no charge. They could also have you send water to them for a comparison. If the kits is under warranty this isn't unheard of.

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[avery155]

Ok so I finally got a reading is shook gently for a little over a minute instead of two, got a reading of 4 which converted to 0.012. . I may have to feed a little more to try and get it up a bit more around 0.03 .

When test was over I pulled vial and the remainder of the reagent had dissolved. I read last night a post from Hanna said the way the test is, the water level being slightly off, shaking for less than 2 min or a small amount of reagent being left over in packet will not skew results. Like others said what will is scratches, air bubbles, dirt, and finger prints. They also highly recommend using same vial for reference and test.

On a side note I checked my alk and it was 13. Last night before my dose it was 8.5 . I'm not too concerned yet since they say don't test until after the first week of dosing calc and all. I'll test it again tonight to see if it drops.

[BrettDS]

Originally Posted by avery155

On a side note I checked my alk and it was 13. Last night before my dose it was 8.5 . I'm not too concerned yet since they say don't test until after the first week of dosing calc and all. I'll test it again tonight to see if it drops.

I would be concerned about this. If you did one dose and your alk went from 8.5 to 13 then you should cut way back on the dose or stop entirely. Frankly, 8.5 is a perfectly acceptable level and if your tank is maintaining alkalinity at 8.5 you probably don’t need to dose at all. But 13 is definitely on the high side and if one dose raises it from 8.5 to 13 you don’t want to add another dose of the same amount or you will be dangerously high. Not to mention that going moving up 4.5dkh in one day is way too fast to be raising alk.

[Dsekula]

Originally Posted by avery155

Ok so I finally got a reading is shook gently for a little over a minute instead of two, got a reading of 4 which converted to 0.012. . I may have to feed a little more to try and get it up a bit more around 0.03 .

When test was over I pulled vial and the remainder of the reagent had dissolved. I read last night a post from Hanna said the way the test is, the water level being slightly off, shaking for less than 2 min or a small amount of reagent being left over in packet will not skew results. Like others said what will is scratches, air bubbles, dirt, and finger prints. They also highly recommend using same vial for reference and test.

On a side note I checked my alk and it was 13. Last night before my dose it was 8.5 . I'm not too concerned yet since they say don't test until after the first week of dosing calc and all. I'll test it again tonight to see if it drops.

Awesome!! Glad to see you got a result. I would be hesitant on dosing based on it due to the shortened reaction time tho. Po4 testing is finicky under the best circumstances. If the issue is the meter shutting off, may I suggest checking it at 1min when you know the meter is still on as this will reset the sleep timer. Then checking it again at 2min which it should now stay on for. If the results is the same after doing this a few times I'd say it's a safe bet to follow the 1min reading but if not you could always just hit that check button an extra time to keep the meter on.

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[avery155]

Originally Posted by BrettDS

I would be concerned about this. If you did one dose and your alk went from 8.5 to 13 then you should cut way back on the dose or stop entirely. Frankly, 8.5 is a perfectly acceptable level and if your tank is maintaining alkalinity at 8.5 you probably don’t need to dose at all. But 13 is definitely on the high side and if one dose raises it from 8.5 to 13 you don’t want to add another dose of the same amount or you will be dangerously high. Not to mention that going moving up 4.5dkh in one day is way too fast to be raising alk.

This was day 4 on dosing 10 ml bionic, levels had not changed any other day except for maybe a small increase in calc. I am going to check again when my wife and I get home I did the test in a rush while she was getting a shower because we have to go to the hospital for a family member. Before when I tested I have always done it before I dose at midnight. This time i testes 10 hours early. I have a red Sea pro foundation kit comming tomorrow to get more accurate results compared to the API. Only reason I started dosing was due to the addition of a 5 inch clam.

All corals and clam look healthy and colorful today.

[Dsekula]

Originally Posted by avery155

This was day 4 on dosing 10 ml bionic, levels had not changed any other day except for maybe a small increase in calc. I am going to check again when my wife and I get home I did the test in a rush while she was getting a shower because we have to go to the hospital for a family member. Before when I tested I have always done it before I dose at midnight. This time i testes 10 hours early. I have a red Sea pro foundation kit comming tomorrow to get more accurate results compared to the API. Only reason I started dosing was due to the addition of a 5 inch clam.

All corals and clam look healthy and colorful today.

+1 for that, definitely double check that result before making a change. Rushing anything with a reef causes problems, even testing lol if that was a true change I would certainly expect some sign from your life stock but I'm sure other more experienced reefers can go into that.

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