Carbon testing

[griff500]

I've long been intrigued by successful tanks that have varying levels of nitrate and phosphate, albeit phosphate is always lower than nitrate, and wondered if the relative level of carbon was the missing link. Perhaps the tanks that thrive on higher levels of nitrate and phosphate have higher levels of carbon than those with lower levels and we've not quite been able to get the balance right because we can only test two of the three nutrients - C, N and P.

Perhaps the results of carbon testing will indicate whether our particular tanks should run with higher or lower relative levels of nitrate and phosphate?

It might be obvious and not new to everyone else but I'm quite excited about the ICP tests giving results for carbon and wondered what everyone else thinks about this.

 

[rkpetersen]

ICP doesn't test for carbon. Carbon is present in seawater in so many different forms; dissolved carbon dioxide, inorganic carbonates, organic molecules of all sizes. Even if there were an accurate test for the level of dissolved organics (DOC, DOM, CDOM) in the aquarium, which is what you're getting at and would be useful to some degree, it still wouldn't tell us which organics, out of thousands of possibilities, were present and in what ratios.

 

[griff500]

ICP doesn't test for carbon. Carbon is present in seawater in so many different forms; dissolved carbon dioxide, inorganic carbonates, organic molecules of all sizes. Even if there were an accurate test for the level of dissolved organics (DOC, DOM, CDOM) in the aquarium, which is what you're getting at and would be useful to some degree, it still wouldn't tell us which organics, out of thousands of possibilities, were present and in what ratios.

The tests from Triton and ATI are about to (or have just started) testing for 'dissolved organic carbon' as far as I understand. If there was no test for it I wouldn't have got excited about it.

It was mentioned in a BRS video and I saw it recently on the ATI website (although I cannot find it now) in relation to their Nutrition CNP product and testing for C becoming available.

 

[rkpetersen]

OK, that'll be interesting!

 

[Chris Villalobos]

Triton is doing N-DOC testing. Just got mine back and it does give more insight. Here are my results.

https://www.reef2reef.com/threads/n-doc-on-its-way.538251/#post-5612110

 

[Dan_P]

I've long been intrigued by successful tanks that have varying levels of nitrate and phosphate, albeit phosphate is always lower than nitrate, and wondered if the relative level of carbon was the missing link. Perhaps the tanks that thrive on higher levels of nitrate and phosphate have higher levels of carbon than those with lower levels and we've not quite been able to get the balance right because we can only test two of the three nutrients - C, N and P.

Perhaps the results of carbon testing will indicate whether our particular tanks should run with higher or lower relative levels of nitrate and phosphate?

It might be obvious and not new to everyone else but I'm quite excited about the ICP tests giving results for carbon and wondered what everyone else thinks about this.

What would you do with the number? Would you have to buy a Triton additive to adjust the number? Is there research on the topic concerning the control of organic carbon in aquaria?

 

[griff500]

What would you do with the number? Would you have to buy a Triton additive to adjust the number? Is there research on the topic concerning the control of organic carbon in aquaria?

I wouldn't be looking to control it but it could give a good indication of where Nitrate and Phosphate should be for balance.

 

[Dan_P]

I wouldn't be looking to control it but it could give a good indication of where Nitrate and Phosphate should be for balance.

Can you give an example?

 

[griff500]

Can you give an example?

I'll mention the Redfield ratio and then quickly move along before anyone gets themselves over-excited - I'm aware of all the arguments about that...

I believe that even if the ideal ratios are not known that C, N and P are linked in terms of ratios in a balanced system. I think that's probably fairly well accepted?

We know that P should be less than N (although I'm sure someone will disagree or cite exceptions). What we don't know is where those levels sit in relation to C because we couldn't test for C.

So the idea is that perhaps successful systems with higher levels of N and P and successful systems with lower levels of N and P do actually have something in common, this being a rough ratio between C, N and P. A higher level of C allowing higher levels of N and P and a lower level of C needing lower levels of N and P, but maintaining a rough ratio. So if we know the level of C in our system then perhaps we can get a rough idea of what N and P levels we should be aiming for to achieve balance in our system. Perhaps the ratios and resulting balance is more important than the actual levels of each nutrient.

Perhaps outbreaks of cyano, for example, are down to too much C in an imbalanced system? Maybe that's a reason why carbon dosing can often seem to result in cyano? I've no idea and no doubt someone will correct me.

Those are the sort of things that are running around in my head.

Feel free to shoot me down in flames with facts.

 

[Dan_P]

I'll mention the Redfield ratio and then quickly move along before anyone gets themselves over-excited - I'm aware of all the arguments about that...

I believe that even if the ideal ratios are not known that C, N and P are linked in terms of ratios in a balanced system. I think that's probably fairly well accepted?

We know that P should be less than N (although I'm sure someone will disagree or cite exceptions). What we don't know is where those levels sit in relation to C because we couldn't test for C.

So the idea is that perhaps successful systems with higher levels of N and P and successful systems with lower levels of N and P do actually have something in common, this being a rough ratio between C, N and P. A higher level of C allowing higher levels of N and P and a lower level of C needing lower levels of N and P, but maintaining a rough ratio. So if we know the level of C in our system then perhaps we can get a rough idea of what N and P levels we should be aiming for to achieve balance in our system. Perhaps the ratios and resulting balance is more important than the actual levels of each nutrient.

Perhaps outbreaks of cyano, for example, are down to too much C in an imbalanced system? Maybe that's a reason why carbon dosing can often seem to result in cyano? I've no idea and no doubt someone will correct me.

Those are the sort of things that are running around in my head.

Feel free to shoot me down in flames with facts.

Thanks for sharing!

I started using a “poor man’s” estimate of organic material by tracking chlorine demand, that is, the amount of chlorine destroyed by a sample of aquarium water. I use the number primarily to judge when to replace the GAC, though tracking the weekly value might turn up something interesting someday, like it increases with a cyanobacteria outbreak. Just for the fun I determined that the chlorine demand of wet skimmate is about 30 times higher than that tank water. I will post the tank chlorine demand data in another month or so when I have another one or two GAC changes performed.

 

[maxwell]

Any help in explaining the test results ,KH low due to calx media needs replacing.
https://www.triton-lab.de/en/showroom/aquarium/auswertung-a/n-doc/3506/

 

[Gareth elliott]

Does the n-doc give you ideas on what to do with that number?

Also what reefers have actually used the red field ratio to the benefit of their tank?

We keep so many corals that are from different depths that have different nutrient levels. Ie that acro from the surf zone to that lps. None of these areas have levels that are perfectly in tune with the ratio and many are quite distant.

 

[maxwell]

Gareth , just raise the KH as its a little low which I knew .The tank is crammed with sps and a few lps. I have no problems but did not understand the tests.

 

[Gareth elliott]

Gareth , just raise the KH as its a little low which I knew .The tank is crammed with sps and a few lps. I have no problems but did not understand the tests.

I just have a hard time wrapping my head around if doc came back low or high why i would adjust [emoji23]

I mean maybe if i was dosing iodine would be useful to know? I dont and have no plans on it, but...

 

[rkpetersen]

Also what reefers have actually used the red field ratio to the benefit of their tank?

My guess is, none.
It's been known for years that the classic Redfield ratio of 106:16:1 only applies to a mixed population of plankton; it's an average.
The actual ratio can vary considerably in the tissues of different specific plankton species.
Benthic algae growing on coral reef surfaces can also very different; one study gave a ratio of 550:30:1.
And it's also usually quite different in the tissues of corals, anemones, etc.
For example another old study showed that the zooxanthellae algae within Tridacna gigas clams had a ratio of 303:52:1.

 

[rkpetersen]

Any help in explaining the test results ,KH low due to calx media needs replacing.
https://www.triton-lab.de/en/showroom/aquarium/auswertung-a/n-doc/3506/

They measure the total carbon present in your sample, which is TC.
Then they remove the CO2 and measure the carbon again, this is TOC (total organic carbon).
You'll notice that the first number listed there, TCO2, is just the difference, subtracting TOC from TC.
Your organic carbon level of 3.8 ppm is reasonable.
For comparison, the TOC level in one of my tanks, which runs sps-heavy with low nutrient levels, measured 1.27 ppm.
Another tank, which has lots of fish and anemones, and has somewhat higher nutrient levels, measured 3.53 ppm.

The second section, with nitrogen information, requires you to input your nitrate level present at the time of the sampling.
The maximum concentration of nitrate that could be in the tank is the N/NO3 number, 3.18 ppm, which is derived from the Total Nitrogen Bound TNb number, 0.72 ppm.
This number represents all of the nitrogen in your system. Your nitrate can't be higher but could be lower.
When you enter the nitrate concentration (which doesn't come from Triton), the bar graph underneath will change.
Triton wants you to have a ratio of nitrate to non-nitrate nitrogen (proteins, etc) of about 3:1, as depicted in the upper bar.
However there isn't really a lot of science behind this recommendation, imo.

The third section, with phosphorus information, also requires you to input data.
This could be from your own phosphorus or phosphate test done at the time of the sampling, or from a concurrent ICP-OES test sent to Triton.
Then the 3 graphs at the bottom show your relationships of carbon, nitrogen and phosphorus.
Triton wants them all to line up at the crossing line.
But again, the science is weak and I wouldn't lose too much sleep if this isn't the case.