Guess the Phosphate level

[Allmost]

well problem is if me a "hobbyist" does experiments, and post them, my results would be considered me seeing what I like to see

like I mean so many Zeo tanks around, and like one in my living room .... ! so would be hard to say what Im looking at is not working or isnt actually there

Carbon dosing I thought was prety much proven ... there are articles and stuff out ... cant be that EVERY one that doses carbon and seeing their N and P come down is just "seeing things" cause they wanted it to happen ... but again the human thought is prety powerful, so might influence test kits [kidding, but it kinda might !]

 

[Thales]

well problem is if me a "hobbyist" does experiments, and post them, my results would be considered me seeing what I like to see

Not if they are documented well and performed honestly. Anyone can do good science. That said, any experiment should scrutinized about conformation bias and other potential issues.

like I mean so many Zeo tanks around, and like one in my living room .... ! so would be hard to say what Im looking at is not working or isnt actually there

Experiments on a full blown system are difficult to parse out because there are so many variables, and often many things are changed at once. I think complexity needs to be reduced and single elements tested.

Carbon dosing I thought was prety much proven ... there are articles and stuff out ... cant be that EVERY one that doses carbon and seeing their N and P come down is just "seeing things" cause they wanted it to happen ... but again the human thought is prety powerful, so might influence test kits [kidding, but it kinda might !]

Again, there are so many influences of methodology applied to a full blown system that it hard to tell what is actually happening. A lot of the reports of N coming down from carbon dosing are on new systems around the time I would expect to see a reduction of algae even without the carbon dosing. I have little doubt that carbon dosing brings down N, some question about it bringing down P as IME with carbon dosing both at home and at work hasn't shown a difference in P. A simple side by side experiment like the inland reef eco aqualizer test would go a long way in directing us.

 

[DogueDeBordeaux]

As I got more lazy about trying to deal with the phosphate, I noticed no real difference in the corals. IMO, phosphate is really the only thing 'out of whack' in my system.


Maybe I missed this, but what has your NO3 level tested at?

 

[Thales]

Last time I tested was in October and it was 9.5

 

[Fredfish]

Looks like a bunch of mulm down there. Almost all the water from the overflows goes through the skimmer before hitting the sump proper. Sometimes I pretend that I am going to grow algae down there, but lately it doesn't seem to be growing well.

No increase in small critters that might consume the mulm?

 

[Allmost]

Looks like a bunch of mulm down there. Almost all the water from the overflows goes through the skimmer before hitting the sump proper. Sometimes I pretend that I am going to grow algae down there, but lately it doesn't seem to be growing well.

then perhaps your N and P are not where u think they are ?

cause algae should grow in elevated po4 and no3, no ?

maybe we are all missing something really huge ...

also would love to know how u test for po4.

 

[Thales]

then perhaps your N and P are not where u think they are ?

cause algae should grow in elevated po4 and no3, no ?

maybe we are all missing something really huge ...

Dunno. I haven't really been trying to grow the algae. The light down there may be bad, something may be eating it, it may be too cold down there - I don't heat the sump anymore, just the DT. Algae grows just find in the DT - they euro bracing acts kinda like an ATS and I have to scrape it every week or two.

I have no reason to think the testing is off. Both the AWT and the tests from work seem to match up and if the work tests are bad, we would be seeing things going wrong at work, which we aren't.

I'll see if I can get a set of tests done this week.

 

[Thales]

No increase in small critters that might consume the mulm?

Dunno. I don't dig around down there. I would assume there would be critters though, its kinda like a big refugium down there.

 

[drdoolittle]

Kinda. Kalk overdose - One in 2009, and one in 2011. Both kalk overdoses, but for different reasons.

http://packedhead.net/2009/epic-fail-–-the-anatomy-of-a-disaster/

http://packedhead.net/2011/p237/

So really, all the SPS growth in my tank is from 2011 and newer.

O


I remember when those happened. Nice recovery man.

 

[JimWelsh]

Sorry, I arrived late for this party....

That is absolutely one of the points I like to make. The questionable reliability of po4 testing, especially at levels reefers have been striving for in the last few years, is another.

I have previously tested the performance of the Merck D-D Phosphate test kit by spiking newly mixed saltwater with a standard made for my by a colleague at the lab I work for, and found it to be reasonably precise and accurate. I'll gladly repeat that test with my current ELOS Pro kit (really the same test), and report back soon.

The last PO4 test I believe was 1.24, tested with the Hach ascorbic acid molybdate method.

Rich, which model of Hach test kit is that? Is it the PO-23?

I found the handheld to give me different results when I retested the same sample several times. That could have been me though.

This indicates an issue with the precision of the testing method, most likely.

The most recent test I have is from December 10. PO43 tested with the Hach ascorbic acid molybdate method 1.134, Alk, 2.88. I should prolly test again and see where the tank is holding now. I'll see what I can do this week.

Your numbers of 1.24 and 1.134 given above are suspiciously precise. Do you really mean that you are able to get 3 and even 4 significant figures of precision out of the test method you are using? I would think that one or at most two sig figs would be possible for such a test. Again, can you please specify the exact model of test kit, so that I can be clear about the range and sensitivity it is supposed to have?

Also, just to be clear, that number is supposed to be Orthophosphate, yes (as opposed to Total phosphate, or some other measure)?

 

[Thales]

Heya Jim!

Ortho, Hach DR5000

Bunch more info here, starting on page 54 (though we are no longer using beach water):

http://www.columbuszoo.org/drumcroaker/pdf/2010.pdf

 

[JimWelsh]

OK, so I get it now -- you're having your tank water tested at work.

Next question: It appears that the calibration curve for the test is being created for standards ranging from 0.0 to 0.5 PPM of PO4, but the sample being tested is way outside the range of this calibration curve. Was a calibration curve developed using standards in the 1.0 to 2.0 PPM range, to establish a valid calibration curve that matched the concentration of the sample being tested?

 

[JimWelsh]

And I find it interesting in the context of this thread that the document for the Phosphate test you linked says, "The tolerance level used by the aquarium was also a standard for the industry, with an upper limit of 0.2 ppm PO43-. The current phosphate levels were within the accuracy range for the HACH testing method. This testing method worked until the tolerance level was lowered from 0.2 ppm PO43- to 0.05 ppm PO43- to better manage the coral exhibits."

This implies that the marine biologists running the Steinhart Aquarium have come to a conclusion that 0.05 ppm is better than 0.2 ppm "to better manage the coral exhibits." Are you able to elaborate what is meant by "better manage" in this context, Rich, and perhaps even what facts, science, or other evidence drove this decision?

 

[Thales]

OK, so I get it now -- you're having your tank water tested at work.

Next question: It appears that the calibration curve for the test is being created for standards ranging from 0.0 to 0.5 PPM of PO4, but the sample being tested is way outside the range of this calibration curve. Was a calibration curve developed using standards in the 1.0 to 2.0 PPM range, to establish a valid calibration curve that matched the concentration of the sample being tested?

Dunno. I'll ask, but at least two other testing methodologies gave similar results.

 

[Thales]

And I find it interesting in the context of this thread that the document for the Phosphate test you linked says, "The tolerance level used by the aquarium was also a standard for the industry, with an upper limit of 0.2 ppm PO43-. The current phosphate levels were within the accuracy range for the HACH testing method. This testing method worked until the tolerance level was lowered from 0.2 ppm PO43- to 0.05 ppm PO43- to better manage the coral exhibits."

This implies that the marine biologists running the Steinhart Aquarium have come to a conclusion that 0.05 ppm is better than 0.2 ppm "to better manage the coral exhibits." Are you able to elaborate what is meant by "better manage" in this context, Rich, and perhaps even what facts, science, or other evidence drove this decision?

That was 4 or 5 years ago, and it was written using the 'common knowledge' that .05 is the range to shoot for that everyone else uses. In the we mention some other tanks that are running at 'elevated' levels, though not as high as the high point my tank has reached, are are no longer shooting for .05, but somewhere between .1 and .2.

 

[JimWelsh]

I have previously tested the performance of the Merck D-D Phosphate test kit by spiking newly mixed saltwater with a standard made for my by a colleague at the lab I work for, and found it to be reasonably precise and accurate. I'll gladly repeat that test with my current ELOS Pro kit (really the same test), and report back soon.

I just repeated this, and have pictures to document what I'm about to report if anybody feels that they are necessary.

The standard my colleague prepared consisted of 0.1435 g of monobasic potassium phosphate (KH2PO4) dissolved in 1.0 L of DI water, giving 100 PPM of PO4.

I first took new, aged IO mixed with RO/DI water at a salinity of 35 PPT, and analyzed 20 mL of it using the ELOS Phosphate Pro kit. The result was 0.000 PPM.

Next, I took 1 L of the same IO mixture, and added 0.24 mL of the 100 PPM PO4 standard described above. That should give a solution with 0.024 PPM of PO4. I analyzed 20 mL of this solution with the ELOS kit, and the result was an intermediate result between the 0.000 and the expected 0.024 PPM PO4 result.

I then took 1 L of the IO mixture, and instead added 0.48 mL of the standard, and analyzed it. The result this time was very close to the 0.024 PPM color on the chart.

Truth be told, this standard was prepared back in June 2009. The colleague who prepared it says that it really shouldn't degrade or deteriorate over time, but as a standard practice he did put an arbitrary expiration date on it, which, coincidentally, is January 2014!

I can have a fresh standard made up, and will gladly repeat the test with a fresh standard.

 

[dkeller_nc]

If you work at a company with chemistry laboratory equipment, they likely have a scanning spectrophotometer. Talk to your colleague about this, but it should be fairly straightforward to construct a calibration curve from testing several different dilutions of the stock standard, then reading them on the spec.

That would be very interesting information from the standpoint of accuracy and precision of the Elos reagents and methodology.

 

[sahin]

I just repeated this, and have pictures to document what I'm about to report if anybody feels that they are necessary.

The standard my colleague prepared consisted of 0.1435 g of monobasic potassium phosphate (KH2PO4) dissolved in 1.0 L of DI water, giving 100 PPM of PO4.

I first took new, aged IO mixed with RO/DI water at a salinity of 35 PPT, and analyzed 20 mL of it using the ELOS Phosphate Pro kit. The result was 0.000 PPM.

Next, I took 1 L of the same IO mixture, and added 0.24 mL of the 100 PPM PO4 standard described above. That should give a solution with 0.024 PPM of PO4. I analyzed 20 mL of this solution with the ELOS kit, and the result was an intermediate result between the 0.000 and the expected 0.024 PPM PO4 result.

I then took 1 L of the IO mixture, and instead added 0.48 mL of the standard, and analyzed it. The result this time was very close to the 0.024 PPM color on the chart.

Truth be told, this standard was prepared back in June 2009. The colleague who prepared it says that it really shouldn't degrade or deteriorate over time, but as a standard practice he did put an arbitrary expiration date on it, which, coincidentally, is January 2014!

I can have a fresh standard made up, and will gladly repeat the test with a fresh standard.

I would be very grateful if you could repeat the test and report back. :thumbsup: I no longer have access to a lab, so cannot make up or get a standard solution.

I tested the D&D Merck kit years ago, as well as the Hanna ULR meter and got VERY reasonable and repeatable results as far as I recall.

I am now using the Elos HiRes Phosphate kit an would love to know how accurate and consistent it is. Many thanks.

 

[Thales]

I just repeated this, and have pictures to document what I'm about to report if anybody feels that they are necessary.

The standard my colleague prepared consisted of 0.1435 g of monobasic potassium phosphate (KH2PO4) dissolved in 1.0 L of DI water, giving 100 PPM of PO4.

I first took new, aged IO mixed with RO/DI water at a salinity of 35 PPT, and analyzed 20 mL of it using the ELOS Phosphate Pro kit. The result was 0.000 PPM.

Next, I took 1 L of the same IO mixture, and added 0.24 mL of the 100 PPM PO4 standard described above. That should give a solution with 0.024 PPM of PO4. I analyzed 20 mL of this solution with the ELOS kit, and the result was an intermediate result between the 0.000 and the expected 0.024 PPM PO4 result.

I then took 1 L of the IO mixture, and instead added 0.48 mL of the standard, and analyzed it. The result this time was very close to the 0.024 PPM color on the chart.

Truth be told, this standard was prepared back in June 2009. The colleague who prepared it says that it really shouldn't degrade or deteriorate over time, but as a standard practice he did put an arbitrary expiration date on it, which, coincidentally, is January 2014!

I can have a fresh standard made up, and will gladly repeat the test with a fresh standard.

Thanks Jim. Seems about what I would expect. Phosphate tests, and many others, seem best for trending purposes, not for accuracy.

 

[AugustWest]

Ever since I got a new box of reagents for my Hanna ULR checker I've been getting readings all over the place... Hanna replaced it for me so now I have 3 different Lot # 's of reagents. Every box gives me a different reading and that's with being very careful during the testing procedure. " Guess the Phosphate" is right .