The myth of N an P trapped on the sand bed

OP
OP
sixty_reefer

sixty_reefer

5000 Club Member
View Badges
Joined
Nov 8, 2018
Messages
5,523
Reaction score
7,833
Location
The Reef
Rating - 0%
0   0   0
as I mentioned, acid will break down some organic P. I personally think there is some different explanation for mist of your result, including interference or partial detection of some organic phosphates.

Organics containing N will not be similarly broken down.
On the nitrates the reagent are:

solution 1

sulphanilic acid
m-phenylenediamine dihydrochloride
hydrogen chloride
H314, h317, h318, h341, h411

solution 2

m-phenylenediamine dihydrochloride
hydrogen chloride
h314, h317, h318, h341, h412
 
OP
OP
sixty_reefer

sixty_reefer

5000 Club Member
View Badges
Joined
Nov 8, 2018
Messages
5,523
Reaction score
7,833
Location
The Reef
Rating - 0%
0   0   0
Hydrochloric can certainly dissolve the sand which would free up any phosphate bound to it, hence the high result, but it’s not organic.
That explains the crazy reaction wend the sample had sand.
According to google sulphuric acid can also melt organics.
 

Randy Holmes-Farley

Reef Chemist
View Badges
Joined
Sep 5, 2014
Messages
66,527
Reaction score
62,817
Location
Arlington, Massachusetts, United States
Rating - 0%
0   0   0
On the nitrates the reagent are:

solution 1

sulphanilic acid
m-phenylenediamine dihydrochloride
hydrogen chloride
H314, h317, h318, h341, h411

solution 2

m-phenylenediamine dihydrochloride
hydrogen chloride
h314, h317, h318, h341, h412

There are no simple kit reagents that can break organic N to give nitrate.
 
OP
OP
sixty_reefer

sixty_reefer

5000 Club Member
View Badges
Joined
Nov 8, 2018
Messages
5,523
Reaction score
7,833
Location
The Reef
Rating - 0%
0   0   0
Last one for phosphates, there is no question about it for me. Left tank water and a piece of macro algae, right tank water only.

C0B0C3B2-E18F-4E8D-92AC-FCE4BEB421B0.jpeg
CDA19792-7635-4896-9CEB-1680ABB48B5D.jpeg
AF77E04A-361B-41F8-8A81-4B7EBD4BCAD1.jpeg
0A0EDEBA-35B4-490A-B0ED-D2C7B46726C9.jpeg
 

Randy Holmes-Farley

Reef Chemist
View Badges
Joined
Sep 5, 2014
Messages
66,527
Reaction score
62,817
Location
Arlington, Massachusetts, United States
Rating - 0%
0   0   0
That explains the crazy reaction wend the sample had sand.
According to google sulphuric acid can also melt organics.

Don’t be misled. This is not an issue with nitrate kits.

Roads lead from NY to LA. But there’s no chance that if you go for a walk at the Statue of Liberty that you might find yourself in LA.
 
OP
OP
sixty_reefer

sixty_reefer

5000 Club Member
View Badges
Joined
Nov 8, 2018
Messages
5,523
Reaction score
7,833
Location
The Reef
Rating - 0%
0   0   0
Don’t be misled. This is not an issue with nitrate kits.

Roads lead from NY to LA. But there’s no chance that if you go for a walk at the Statue of Liberty that you might find yourself in LA.
If you look at the post above I just extracted phosphates from a macro algae with this test kit, on a 10 minute test. It’s unquestionably now for me that micro algaes influence my phosphates.

edit: below is similar test with a piece of macro algae that extracted 5ppm of nitrates in 10 minutes. Have you got any hypotheses on why my test kits are extracting phosphates and nitrates from organic organisms?
 
Last edited:
OP
OP
sixty_reefer

sixty_reefer

5000 Club Member
View Badges
Joined
Nov 8, 2018
Messages
5,523
Reaction score
7,833
Location
The Reef
Rating - 0%
0   0   0
Nitrates here’s my conclusion:
Both vessels are in RO, vessel on the right is control to illustrate that there is no nitrates presence, vessel on the left is the same with a large piece of macro algae. 5ppm of nitrates extracted from a piece of macro algae under 10 minutes. I don’t mind doing a full 10 minute video on the phosphates or nitrates test.

77F7A504-A583-4F9B-A107-FB12E7E21153.jpeg
9D309829-A6BD-4EFB-B34A-F140F210F833.jpeg

6E44F245-1B75-47A1-9D27-FB6F0A8B60AE.jpeg

B7A20E0F-F347-4D8F-8991-E4D2FAC8C011.jpeg
 

taricha

5000 Club Member
View Badges
Joined
May 22, 2016
Messages
6,483
Reaction score
9,994
Rating - 0%
0   0   0
@sixty_reefer you are correct that there is considerable PO4 bound to aragonite. I don't think there is much nitrogen. Certainly not much NO3.

There's a couple of issues with doing the test like are shown here.
If any of the chemicals in the test kit react with the aragonite sand (any acid will, and both the PO4 and NO3 tests will have some acid) - then you have so much aragonite there that it will completely react away the test kit chemical and now the designed reactions of the kit don't occur.
Also the aragonite will prevent the test kit from reaching the pH's it was supposed to reach for various steps, so again, the designed reactions may not occur.
And also, the dissolution of the aragonite makes the sample water have far more dissolved material (of various kinds) in it than normal saltwater should have.
All of that is to say that the test kits are basically being run on water that is light-years away from the parameters where the test kit results can be interpreted confidently.

If you want to probe the chemistry of the sandbed there's a couple of not-crazy ways to do it.

1) easiest is porewater: draw water from between the sand grains slowly up through a ~1um syringe filter, the filter will keep the big particles out and a later filtration through 0.2-0.4um filter can make sure you aren't just testing particles.
If you do this carefully, you'll find higher PO4 than tank water aragonite holds higher PO4 in the sandbed than above it in my experience, but not much N (NH4,NO2,NO3). If you draw in very anoxic water (with a bad smell) you'll need to aerate out the hydrogen sulfide. It wrecks the PO4 test.

2) You could pre-dissolve a known amount of aragonite sand with HCl, and dilute that resulting sample way down with aquarium water to make the things you are looking for within the test kit range and pH correct it, then run tests on it. You can then calculate how many mg of P you got from mg of aragonite.

3) you could analyze the fine "fluff" particles that are slow to settle out of a shaken sandbed. They are fine enough that you can dilute them and test very tiny amounts of them and run them through the digestions required for determining total organic C and N and P.

This is what I got back some time ago when doing this on my sandbed fluff....

mass %'s --->C %N %P %Fe %Ca %% HCl insoluble
12/11 Silt0.178%0.054%
12/11 Silt (former cyano mat)0.198%0.106%
12/08 Silt (former cyano mat)4.42%0.59%0.172%0.069%23.0%25%
12/07 Silt4.30%0.61%0.180%0.142%27.9%14%
12/07 Silt4.49%0.156%
12/06 Silt0.178%0.151%
12/06 Silt0.178%
11/16 Silt4.5%0.79%0.187%
9/30 Silt4.1%0.183%

The C N P are done with separate hanna kits for total organic C, total N and Total P. These involve heated digestions in loads of strong acid where I had to take the fluffy sandbed material, dilute it in DI water because saltwater Chloride wrecks all of these. You run it in a heating block for a set amount of time up to 2 hrs in a closed tube - some as hot as 150C (yikes!)

The last two ( Fe and Ca) were simply done by dissolving the material in HCl and then diluting a bunch and pH correcting then running a Ca titration or a chemical Fe test. The Ca result is telling me that most of the fluffy material is probably fine particles of aragonite CaCO3.

The organic C and N levels probably just represent the amount of dead microorganisms in the fluff. But the P is higher than expected if the level of C and N represent organisms. It again indicates PO4 bound to aragonite particles, but the Fe test results may also mean that some amount of P is bound in Fe compounds.

Mostly I'm sharing this to say that trying to do chemical tests on particles is most likely to just give you results that are impossible to interpret unless you use something that's meant specifically to handle that kind of thing.
 
OP
OP
sixty_reefer

sixty_reefer

5000 Club Member
View Badges
Joined
Nov 8, 2018
Messages
5,523
Reaction score
7,833
Location
The Reef
Rating - 0%
0   0   0
@sixty_reefer you are correct that there is considerable PO4 bound to aragonite. I don't think there is much nitrogen. Certainly not much NO3.

There's a couple of issues with doing the test like are shown here.
If any of the chemicals in the test kit react with the aragonite sand (any acid will, and both the PO4 and NO3 tests will have some acid) - then you have so much aragonite there that it will completely react away the test kit chemical and now the designed reactions of the kit don't occur.
Also the aragonite will prevent the test kit from reaching the pH's it was supposed to reach for various steps, so again, the designed reactions may not occur.
And also, the dissolution of the aragonite makes the sample water have far more dissolved material (of various kinds) in it than normal saltwater should have.
All of that is to say that the test kits are basically being run on water that is light-years away from the parameters where the test kit results can be interpreted confidently.

If you want to probe the chemistry of the sandbed there's a couple of not-crazy ways to do it.

1) easiest is porewater: draw water from between the sand grains slowly up through a ~1um syringe filter, the filter will keep the big particles out and a later filtration through 0.2-0.4um filter can make sure you aren't just testing particles.
If you do this carefully, you'll find higher PO4 than tank water aragonite holds higher PO4 in the sandbed than above it in my experience, but not much N (NH4,NO2,NO3). If you draw in very anoxic water (with a bad smell) you'll need to aerate out the hydrogen sulfide. It wrecks the PO4 test.

2) You could pre-dissolve a known amount of aragonite sand with HCl, and dilute that resulting sample way down with aquarium water to make the things you are looking for within the test kit range and pH correct it, then run tests on it. You can then calculate how many mg of P you got from mg of aragonite.

3) you could analyze the fine "fluff" particles that are slow to settle out of a shaken sandbed. They are fine enough that you can dilute them and test very tiny amounts of them and run them through the digestions required for determining total organic C and N and P.

This is what I got back some time ago when doing this on my sandbed fluff....

mass %'s --->C %N %P %Fe %Ca %% HCl insoluble
12/11 Silt0.178%0.054%
12/11 Silt (former cyano mat)0.198%0.106%
12/08 Silt (former cyano mat)4.42%0.59%0.172%0.069%23.0%25%
12/07 Silt4.30%0.61%0.180%0.142%27.9%14%
12/07 Silt4.49%0.156%
12/06 Silt0.178%0.151%
12/06 Silt0.178%
11/16 Silt4.5%0.79%0.187%
9/30 Silt4.1%0.183%

The C N P are done with separate hanna kits for total organic C, total N and Total P. These involve heated digestions in loads of strong acid where I had to take the fluffy sandbed material, dilute it in DI water because saltwater Chloride wrecks all of these. You run it in a heating block for a set amount of time up to 2 hrs in a closed tube - some as hot as 150C (yikes!)

The last two ( Fe and Ca) were simply done by dissolving the material in HCl and then diluting a bunch and pH correcting then running a Ca titration or a chemical Fe test. The Ca result is telling me that most of the fluffy material is probably fine particles of aragonite CaCO3.

The organic C and N levels probably just represent the amount of dead microorganisms in the fluff. But the P is higher than expected if the level of C and N represent organisms. It again indicates PO4 bound to aragonite particles, but the Fe test results may also mean that some amount of P is bound in Fe compounds.

Mostly I'm sharing this to say that trying to do chemical tests on particles is most likely to just give you results that are impossible to interpret unless you use something that's meant specifically to handle that kind of thing.
Thank you for the information is very appreciated, I did thought that aragonite could somehow influence the first results and some how skyrocket, from there I moved to try and remove the aragonite variable and not used the aragonite in any other test. I did done some that I can’t explain, there is more examples along the thread but this two for me kind of tell me that this test kit somehow can be influenced by organic matter in the water column. On this two examples below macro algae was added to the samples and I was able to get a reading of nitrates and phosphates, do you have a idea on what could influence the test wend only macro algae was added?


Last one for phosphates, there is no question about it for me. Left tank water and a piece of macro algae, right tank water only.

C0B0C3B2-E18F-4E8D-92AC-FCE4BEB421B0.jpeg
CDA19792-7635-4896-9CEB-1680ABB48B5D.jpeg
AF77E04A-361B-41F8-8A81-4B7EBD4BCAD1.jpeg
0A0EDEBA-35B4-490A-B0ED-D2C7B46726C9.jpeg

Nitrates here’s my conclusion:
Both vessels are in RO, vessel on the right is control to illustrate that there is no nitrates presence, vessel on the left is the same with a large piece of macro algae. 5ppm of nitrates extracted from a piece of macro algae under 10 minutes. I don’t mind doing a full 10 minute video on the phosphates or nitrates test.

77F7A504-A583-4F9B-A107-FB12E7E21153.jpeg
9D309829-A6BD-4EFB-B34A-F140F210F833.jpeg

6E44F245-1B75-47A1-9D27-FB6F0A8B60AE.jpeg

B7A20E0F-F347-4D8F-8991-E4D2FAC8C011.jpeg
 
OP
OP
sixty_reefer

sixty_reefer

5000 Club Member
View Badges
Joined
Nov 8, 2018
Messages
5,523
Reaction score
7,833
Location
The Reef
Rating - 0%
0   0   0
@taricha two more examples were different results were obtain by filtering one of the samples, this one’s I was just testing water and apparently organics like micro algae influence my results.


My test kit got the potential to be different some how.
I thought it would beneficial for me to follow my instinct, I’ve performed 2 test on my phytoplankton culture one is filtering the phytoplankton with a paper towel (all I had to hand) until the culture brine runs clear and on another vial just add phytoplankton culture straight including the live algae.
Both samples were diluted in the same percentage.

99B2FA10-B1C4-4C65-848E-414B0A9744CA.jpeg



3B2507D7-C605-4B7F-83EB-1DA178D556D8.jpeg

With my test kit appears that micro algaes will influence the overall results of the test.
the camera can capture that the vial on the right is slightly darker than the vial to the left.

And lastly my tank, this time filtered with two cotton pads, I feed my system constantly phytoplankton, the difference is not much maybe around 0.02 ppm to 0.03 ppm and wouldn’t create a large issue as I run my system at 0.1 ppm. The story could be different if I was to run my system at 0.02 ppm.


E8DFAB3B-E959-43DC-8740-B073036CB46E.jpeg


is this the reason we have to allow for a 0.02 ppm error margin in some test kits?
 

taricha

5000 Club Member
View Badges
Joined
May 22, 2016
Messages
6,483
Reaction score
9,994
Rating - 0%
0   0   0
On this two examples below macro algae was added to the samples and I was able to get a reading of nitrates and phosphates, do you have a idea on what could influence the test wend only macro algae was added?
same as earlier. This is putting a ton of solid material in a test that's meant to be run on only dissolved nutrients in seawater.

Say that test vial is 10mL and you are looking for 0.1ppm PO4 or 10ppm NO3 that represents
0.001 mg of PO4 or 0.1 mg of NO3 actually in the vial.
and you have the vial packed with 100's of mg of living tissue, and all sorts of compounds that could be above the interference levels of the test kits.
It would be very surprising if the test could generate real results under those circumstances.
And even if it did give you a real result, what would it tell us?
It's only recovering like a zillionth of a percent of the actual N or P in the algae in the vial. Not sure what that's supposed to mean.
 
OP
OP
sixty_reefer

sixty_reefer

5000 Club Member
View Badges
Joined
Nov 8, 2018
Messages
5,523
Reaction score
7,833
Location
The Reef
Rating - 0%
0   0   0
same as earlier. This is putting a ton of solid material in a test that's meant to be run on only dissolved nutrients in seawater.

Say that test vial is 10mL and you are looking for 0.1ppm PO4 or 10ppm NO3 that represents
0.001 mg of PO4 or 0.1 mg of NO3 actually in the vial.
and you have the vial packed with 100's of mg of living tissue, and all sorts of compounds that could be above the interference levels of the test kits.
It would be very surprising if the test could generate real results under those circumstances.
And even if it did give you a real result, what would it tell us?
It's only recovering like a zillionth of a percent of the actual N or P in the algae in the vial. Not sure what that's supposed to mean.
Besides this test kit being able to demineralise organics not much. There was a difference of approximately 0.02 ppm on a test performed to the water column by filtering. The importance of the test will be how much affect a 0.02 ppm can have to a system if more brands are similar.
Imo there is a difference in testing for total phosphates and inorganic phosphate alone. This test seems to be able to test total phosphates
 

Randy Holmes-Farley

Reef Chemist
View Badges
Joined
Sep 5, 2014
Messages
66,527
Reaction score
62,817
Location
Arlington, Massachusetts, United States
Rating - 0%
0   0   0
If you look at the post above I just extracted phosphates from a macro algae with this test kit, on a 10 minute test. It’s unquestionably now for me that micro algaes influence my phosphates.

edit: below is similar test with a piece of macro algae that extracted 5ppm of nitrates in 10 minutes. Have you got any hypotheses on why my test kits are extracting phosphates and nitrates from organic organisms?

You ignore the likely effect that the algae messes with the test chemicals.

I don’t mean to be harsh, but it is not useful to try to subvert well established chemistry to do something different without understanding chemistry.

The Hach method shows what needs to be done to even detect dissolved organic phosphate. It won’t detect all the P in big chunks of algae and their experts have studied testing for many decades.
 
Last edited:

MnFish1

10K Club member
View Badges
Joined
Dec 28, 2016
Messages
22,558
Reaction score
21,785
Rating - 100%
1   0   0
same as earlier. This is putting a ton of solid material in a test that's meant to be run on only dissolved nutrients in seawater.

Say that test vial is 10mL and you are looking for 0.1ppm PO4 or 10ppm NO3 that represents
0.001 mg of PO4 or 0.1 mg of NO3 actually in the vial.
and you have the vial packed with 100's of mg of living tissue, and all sorts of compounds that could be above the interference levels of the test kits.
It would be very surprising if the test could generate real results under those circumstances.
And even if it did give you a real result, what would it tell us?
It's only recovering like a zillionth of a percent of the actual N or P in the algae in the vial. Not sure what that's supposed to mean.
Also - if you use 'RODI' as compared to salt water, you are going to release a LOT of 'stuff' from your macro algae - that theoretically could react with the tests - that have nothing to do with measuring NO3 or PO4.
 
OP
OP
sixty_reefer

sixty_reefer

5000 Club Member
View Badges
Joined
Nov 8, 2018
Messages
5,523
Reaction score
7,833
Location
The Reef
Rating - 0%
0   0   0
Also - if you use 'RODI' as compared to salt water, you are going to release a LOT of 'stuff' from your macro algae - that theoretically could react with the tests - that have nothing to do with measuring NO3 or PO4.
What’s the 3 things that algae release into the water column as they deteriorate? To my knowledge phosphate, nitrates and carbohydrates are the first to get into the water column during demineralisation.
I’ve only used Ro on the nitrates test
 
Last edited:
OP
OP
sixty_reefer

sixty_reefer

5000 Club Member
View Badges
Joined
Nov 8, 2018
Messages
5,523
Reaction score
7,833
Location
The Reef
Rating - 0%
0   0   0
You ignore the likely effect that the algae messes with the test chemicals.

I don’t mean to be harsh, but it is not useful to try to subvert well established chemistry to do something different without understanding chemistry.

The Hach method shows what needs to be done to even detect dissolved organic phosphate. It won’t detect all the P in big chunks of algae and their experts have studied testing for many decades.
I’m not saying that is testing all organics, maybe partially. The lamotte test that I’ve shared earlier demonstrated extracting nitrates and phosphates from organics matter In a similar way. Just a two part solution without boiling, This leaves enough room to be possible, not confirmed. I don’t know if the reagents in the LaMotte test are similar to the reagents used by JBL. Hatch is not the only method used by lab professionals to determine phosphates, nitrates and other nutrients in farming, soil and saltwater testing are fairly similar, with similar trace variables.
 
Last edited:

MnFish1

10K Club member
View Badges
Joined
Dec 28, 2016
Messages
22,558
Reaction score
21,785
Rating - 100%
1   0   0
What’s the 3 things that algae release into the water column as they deteriorate? To my knowledge phosphate, nitrates and carbohydrates are the first to get into the water column during demineralisation.
I’ve only used Ro on the nitrates test
The comment related to the fact that putting that big of a piece into hypotonic water is going to lyse cells - releasing proteins, Amino acids, My point being that you are rapidly going to get many compounds that would NOT be released in a salt water tank. If you had a tank with as much algae in it as in the vial you showed - perhaps - but that ratio of amount of algae to water in the vial is far far higher than I have ever seen in a tank.
 
OP
OP
sixty_reefer

sixty_reefer

5000 Club Member
View Badges
Joined
Nov 8, 2018
Messages
5,523
Reaction score
7,833
Location
The Reef
Rating - 0%
0   0   0
The comment related to the fact that putting that big of a piece into hypotonic water is going to lyse cells - releasing proteins, Amino acids, My point being that you are rapidly going to get many compounds that would NOT be released in a salt water tank. If you had a tank with as much algae in it as in the vial you showed - perhaps - but that ratio of amount of algae to water in the vial is far far higher than I have ever seen in a tank.
I see your point, in a normal situation I wouldn’t be putting a piece of macro algae into a test tube :)
To me, and only me as I have a constant supply of micro algaes to my system this test kit can lead me into zero inorganics without me realising it. I’ve concluded that if I want to know my real inorganic nutrients that I must filter my samples before testing. Or just buy a different brand that doesn’t get affected by micro algae in the water column.
 

Randy Holmes-Farley

Reef Chemist
View Badges
Joined
Sep 5, 2014
Messages
66,527
Reaction score
62,817
Location
Arlington, Massachusetts, United States
Rating - 0%
0   0   0
I’m not saying that is testing all organics, maybe partially. The lamotte test that I’ve shared earlier demonstrated extracting nitrates and phosphates from organics matter In a similar way. Just a two part solution without boiling, This leaves enough room to be possible, not confirmed. I don’t know if the reagents in the LaMotte test are similar to the reagents used by JBL. Hatch is not the only method used by lab professionals to determine phosphates, nitrates and other nutrients in farming, soil and saltwater testing are fairly similar, with similar trace variables.


I'm aware of testing methods. Extracting and converting are not the same. Don't confuse them.
 

HBtank

Valuable Member
View Badges
Joined
Jun 6, 2022
Messages
1,606
Reaction score
2,215
Location
Huntington Beach
Rating - 0%
0   0   0
Seems like this shows “dirty” samples are biased high, which is unsurprising. I don’t think the results from the biased samples are meaningful though.
 

A worm with high fashion and practical utility: Have you ever kept feather dusters in your reef aquarium?

  • I currently have feather dusters in my tank.

    Votes: 63 36.6%
  • Not currently, but I have had feather dusters in my tank in the past.

    Votes: 59 34.3%
  • I have not had feather dusters, but I hope to in the future.

    Votes: 24 14.0%
  • I have no plans to have feather dusters in my tank.

    Votes: 26 15.1%
  • Other.

    Votes: 0 0.0%
Back
Top