The myth of N an P trapped on the sand bed

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I’ve done one more test as suggested earlier and this time I’ve mixed 5ml of sand with 20ml of tank water, removed 10ml of water contain organics in suspense to test vial and performed the test as normal. Known parameters from the tank is 10ppm nitrates and 0.1ppm phosphates. I got the following results from todays sample.

91B0C316-8B77-4597-9794-A16EF2D115C9.jpeg


this was the results for yesterday with sand

5383145B-8181-48BC-B51D-3742ADE9871E.jpeg


3C1B9EAF-8A78-4E56-AEDE-8E6096D33C69.jpeg



Randy was righ and the reagent must of removed all the phosphates from the sand on the testing from yesterday.
And there is a small chance that the reagents in the test kit used being able to dissolve the organics and make them available to the colouration reagent.
 
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Could you explain in more detail what the aims are here?

If I understand correctly you are wanting to develop a more accurate phosphorus test?

We know that detritus collects in the sand if not vacuumed etc why is testing the sand going to help here?
The idea come from a different discussion where we where discussing ideas to produce a diy DOC testing.
the results of me testing sand are useless at the moment just something interesting, probably similar to test water, why do we test water? I test my water to know what’s available at given point of the test, sand testing could anecdotally tell me how much is in the sand before it reaches the water column.
 
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It's a thought provoking experiment. If it could be done in a proper lab with control samples and different age sand, water tests done on the water column to determine parameters before tests etc, it would be a worthy line of enquiry because it's often been a question I've seen come up as to how much nutrients does the sandbed trap, how it releases and whether vacuuming the sandbed is beneficial or not.

I'll be watching this one closely to see how you get on
That’s my thoughts also, someone with a lab could develop the idea much further and most likely have a good use for it. On this thread my testing is unreliable and just curiosity maybe develop to a interesting discussion.
 
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The elephant in the room is how to remediate it in the sand bed rather than the water column, should this be the case. Following.
That’s my thought also, reducing nutrients in the water column is fairly easy in my opinion, vacuuming the sand more often should be one of the most common ways to go.
this could explain why we see hair algae growing on the sand bed often.
 

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I would think organic sources of N and P are even more abundant in the sand bed.

Perhaps do a alkaline persulfate digestion test for total nitrogen, and a heat digestion test for total phosphorus. This would paint a even clearer picture.

Or perhaps one can do a BOD test on the supernatant of the sand-water mixture.
 

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That’s my thought also, reducing nutrients in the water column is fairly easy in my opinion, vacuuming the sand more often should be one of the most common ways to go.
this could explain why we see hair algae growing on the sand bed often.
That is what I have found as well. You potentially can have 0 nitrates and phosphates in your water column, but a much higher number at the surface of the sandbed. This will produce algae on the sand and confuse people on why it is there. Shallow sand beds can be nitrate and phosphate batteries, and must be vacuumed regularly to maintain lower nutrients, in my experience. I find that a low amount of people in my area actually vacuum their sand to remove detritus.
 
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I would think organic sources of N and P are even more abundant in the sand bed.

Perhaps do a alkaline persulfate digestion test for total nitrogen, and a heat digestion test for total phosphorus. This would paint a even clearer picture.

Or perhaps one can do a BOD test on the supernatant of the sand-water mixture.
I believe I may be able to perform a BOD5 and a BOD21, mainly for the fun and experience of sound one, the other ones may not be suitable for my kitchen :)
 
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That is what I have found as well. You potentially can have 0 nitrates and phosphates in your water column, but a much higher number at the surface of the sandbed. This will produce algae on the sand and confuse people on why it is there. Shallow sand beds can be nitrate and phosphate batteries, and must be vacuumed regularly to maintain lower nutrients, in my experience. I find that a low amount of people in my area actually vacuum their sand to remove detritus.
Exactly, maybe we see the same thing on dinoflagellates, we’re there’s no nutrients in the water column but plenty on the sand bed. Maybe the reason Cyanobacteria and dinoflagellates prefer to colonise the aragonite surfaces of our systems.
In a way they could be preventing this nutrients to reach the water column by covering this surfaces.

I’m also guilty of not vacuuming the sand bed, I used to do it every couple of days and now is just whenever I remember of doing it. Obviously after this I will ensure I will keep up with it more often, maybe retest after vacuuming and see if that makes a difference.
 
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I believe I may be able to perform a BOD5 and a BOD21, mainly for the fun and experience of sound one, the other ones may not be suitable for my kitchen :)
The BOD test results could be very interesting.

Perhaps you can do it with the tank water as a control.
Tank water vs. Supernatant of sand + fresh sea water.
 
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The BOD test results could be very interesting.

Perhaps you can do it with the tank water as a control.
Tank water vs. Supernatant of sand + fresh sea water.
That’s a really good idea, will order the items I need to perform the test, should be a interesting learning curve.
 

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following along. But gave me a idea about testing the water/sand idea. Just like the above video...taking a scoop of sand/water sample and then draining the water and test that water so prevent any reaction from chemicals with sand..
 

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wow saw your recent post of test.. makes me feel good that my 300 is bare bottom except for a small area where there is 10 pounds of sand for wrasse.
 
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wow saw your recent post of test.. makes me feel good that my 300 is bare bottom except for a small area where there is 10 pounds of sand for wrasse.
It’s crazy that that second test produced a decent amount of residual still, bare in mind that my system doesn’t have any nuisance issues, i can only imagine what the results could be in a system struggling with nuisance, taking that the nutrients would be a major factor for algae bloom.
 

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It’s crazy that that second test produced a decent amount of residual still, bare in mind that my system doesn’t have any nuisance issues, i can only imagine what the results could be in a system struggling with nuisance, taking that the nutrients would be a major factor for algae bloom.
Or.... Those cyanos will suck all the nutrients right up.
 

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Id like to see the same test pulled through a .5 micron filter (or less) to eliminate any concern of particles of sand in the sample.
 

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That would probably pull out some detrital particles as well?
Yes thats the purpose to have clean water that doesnt have anything to interfere with the results.

Fwiw i tried this experiment myself before and after. I measured 1.02ppm po4. Added new aragonite fone sand to 2.5 liters of water. Stirred it and tested some water that I filtered with a paper towel pushed through with a syringe. Results were higher after the aragonite was added at 1.34ppm po4. It doesnt work for me.
 

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Yes thats the purpose to have clean water that doesnt have anything to interfere with the results.

Fwiw i tried this experiment myself before and after. I measured 1.02ppm po4. Added new aragonite fone sand to 2.5 liters of water. Stirred it and tested some water that I filtered with a paper towel pushed through with a syringe. Results were higher after the aragonite was added at 1.34ppm po4. It doesnt work for me.
Perhaps a syringe filter could provide a better filtering effect.

Then again I feel these particles contribute significantly to the "trapped nutrients". So it would probably worth while to quantify them, difficult as it may be.
 
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Yes thats the purpose to have clean water that doesnt have anything to interfere with the results.

Fwiw i tried this experiment myself before and after. I measured 1.02ppm po4. Added new aragonite fone sand to 2.5 liters of water. Stirred it and tested some water that I filtered with a paper towel pushed through with a syringe. Results were higher after the aragonite was added at 1.34ppm po4. It doesnt work for me.
It worked in a way for you 0.32ppm different in a fairly diluted sample like that is still something, the reason I’m not filtering is to catch all the particular organics that are on the sand bed before they become dissolved nitrates and phosphates. What I’m starting to believe is that the reagents in some test kits have the ability to break down organic and test for total nitrogen, this includes particular organics that usually are only found in detritus build up and on the sand bed, if I was to filter the samples I would just be testing aquarium water.
The samples I took had a 5ml of sand to 10ml of water making the organics more concentrated on the samples.
The idea behind is to see if is possible to quantify Particular organics nutrients before they become Dissolved organic and inorganic Nutrients.
dissolved organic and inorganic nutrients will be in the water column particular organic nutrients will be trapped in the sand bed and detritus in my thoughts.
The thing that could be interesting here is that it may be possible to test for particular organic nutrients with a standard test kit.
 
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Perhaps a syringe filter could provide a better filtering effect.

Then again I feel these particles contribute significantly to the "trapped nutrients". So it would probably worth while to quantify them, difficult as it may be.
That’s my thoughts as well, and the centre of the thread. I didn’t knew that our home test kits could potentially have the ability to dissolve organics in the vials and make them available to interpret in ppm on a test kit.
this could also indicate that wend we test out water column we could potentially be testing for organic nutrients in the water column and not just inorganic nutrients as we always believed we where doing.
I don’t know about you, but it makes me think that the accuracy of the test at home could be influenced depending on the organics on the water colum.
Example. Testing phosphates after dosing phytoplankton could in a way affect the accuracy of the test as it may break down the phytoplankton in the vial and make those phosphates show as inorganic nutrient making us believe that there is more phosphates that we actually have. Same if we were to test after feeding etc…
 
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