Relation between detritus and nitrates?

[FranklinDattein]

Hi all,

I am curious about the relation between detritus and nitrates.

It is well known that acumulation of detritus will cause nitrates. It is also known the denitrification system will break nitrates down into nitrogen, which will be released in the atmosphere.
However, the detritus aren't broken down and stay in the tank.

Assuming a stable tank, with a good enough denitrification system and zero or nearly zero nitrates:
- Can areas with high concentration of detritus, have higher nitrates in relation to the rest of the tank? For example, a cave in the live rock or corner of a sump.
- Can detritus carry nitrates or be harmful if it touches corals? For example, if we turkey blast an area full of detritus and it gets pumped int othe display.
- Once the nitrates produced by a chunk of detritus is broken down, can it produce nitrates again?

My guess is that organic matter will decompose, generate detritus and nitrates. Nitrates will be consumed by the denitrification system, leaving only harmless detritus. Makes sense?

 

[brandon429]

this is my take

the denitrification system hardly occurs in reef tanks, it was over touted in the 2000s and thats why stacks of live rock typically cause nitrate through retention of detritus, not lower it. We needed biopellets, carbon dosing, denitrator coils, plant arrangements, and its not occuring for the masses in their live rock and sand -at levels we can consistently repeat, measure or benefit by- or those others wouldnt be needed, so, that begins accumulation in most tanks, not degassing to n2 gas. the nitrate in most reef tanks is accumulating, awaiting export or binding, its not leaving as a gas. tiny portions are, so tiny they dont benefit us mostly. the ability for live rock and ls to degas nitrate has been overstated 99% as a measurable benefit...sure its occuring at trace levels though.

deamination is when amino acids from proteins are broken down and the ammonia released is capitalized by oxidizers where the end point is nitrate. once a protein breaks down into amino acids and then into those constituents by digestion or other destructive means that portion of n has been converted and wont keep re releasing, it tends to hover as a gas in solution until bound up by plants or exported in some way. This is why skimmers affect nitrate, not the gas itself but by removing proteins and amino acids holding nitrogen before its converted in amino acid deamination.

no harm to corals, they have sloughing mechanisms for removing silt and detritus is covered. its a decent food source for some of them due to bacterial aggregates that are eating away at the detritus floc.

areas of higher or lower no3 w be affected by flow and orgin concentrations of waste, so that varies. the currents we employ tend to evenly distribute the waste around our tank. detritus isnt pure proteins either, its chitin shell outcasts from tank bugs, some plant matrix mid decay, several things that might not have as much n to offer as the meaty portions. detritus tends to attract other living creatures like bacteria and they are made up of proteins, so typically if you can see piles of brown collecting somewhere thats at least a portion of actual proteins mid or post breakdown and its leaking some nutrients into your tank. the effects of that range between tanks, some people concern greatly over it and some dont, the dilutions of our tanks helps in that choice.
B

 

[FarmerTy]

Very well said Brandon! I definitely agree with the lack of harm to corals and for the breakdown of what we are really looking at with detritus.

My viewpoint on live rock is slightly different, but only because I try to source larger rocks. I agree that live rock is not the nitrate destroying factories we were always led to believe, however, I believe that large rocks can contribute greatly to denitrification. Denitrification is an anaerobic process, no oxygen, so that's why its most efficient in the deepest recesses of live rock, deep sand beds, and for me personally, the centers of my marinepure ceramic blocks in low flow environments.

For me, I try to buy very large rocks for my tank. In my 215, I have 3 rocks on the right side of the tank that weigh 80lbs by themselves, dry. For me, the deeper the rock, the higher ability to perform denitrification. I would do a deep sandbed too for this purpose but deep sandbeds are eyesores to me. I instead added 2 ceramic blocks in low flow areas in the sump and also run biopellets. Why you may ask am I trying to export so much nitrates? It's because I don't do water changes ever and I don't remove detritus ever because I don't perform any mechanical removal of detritus, other than what may get sucked up in my skimmer.

So with no water changes, nor any mechanical filtration, the detritus just sits in my sump. I did this same style system in my 125 for 3 years with no ill effect. I had about a 1/2"-1" layer of detritus in my sump! I'm at 1.5 years with my 215 currently. Everything is looking pretty good still.

 

[brandon429]

Your tank represents a neat test for this thread, it would be neat to see what the live rock alone does to maintain your current levels, removing no detritus, for two mos w no other supports. thats the only way to know how much it helps, and i do agree 80lb is a bad boy chunk lol that increases those trace levels. i say do the test, then we'll really know the effects of natural nitrate redux

 

[Nano sapiens]

I would say that denitrification is typically incomplete in the majority of reef tanks, thus the many posts lamenting the rise of nitrates.
The main issues are a lack of a contiuous/sufficient food source (carbon) in many tanks for denitrifying bacteria to utilize to breakdown nitrate into nitrogen gas, which then mostly vents into the atmosphere. Another is that the buildup of detritus physically prevents sufficient flow to the aerobic/anerobic coupled bacteria in the substrate, so their efficiency is impaired. And finally, just having a large amount of detritus decomposing in an aquarium adds a constant source of nutrients that can lead to a eutrophic system.

I stir up my LS daily to provide detritus (and it's attached micro-fauna/flora) as a food source for my filter-feeders.

 

[Nano sapiens]

.

 

[Randy Holmes-Farley Verified Community Expert]

Detritus is organic matter perhaps also with inorganic matter like calcium carbonate, but that's not important for this question).

Organic matter will be broken down when taken up into bacteria, and some slower degradation will take place just when loose in the water column. Eventually some organic and inorganic matter remains that is largely resistant to further degradation. In the ocean, some of the organic matter has been present for hundreds of years because it is very resistant to biodegradation.

Some nutrients may have a locally higher concentration in detritus if the water flow around it is very low (like in a sand bed or a hole in a rock.

Bits of detritus blowing around in the current are not going to have appreciably high nutrient levels around it because it will rapidly move away by diffusion and convection.

FWIW, I have let a thick mud of detritus accumulate on the bottom of my sumps and refugia, but I'm not trying to keep a ULNS system.

 

[Amoo]

I'm glad you mentioned marinepure blocks FarmerTy as I was thinking about this study which has already been done:

http://www.cermedia.com/MarinePure Project Report.pdf

 

[Randy Holmes-Farley Verified Community Expert]

I'm glad you mentioned marinepure blocks FarmerTy as I was thinking about this study which has already been done:

http://www.cermedia.com/MarinePure Project Report.pdf

FWIW, I'd personally avoid aluminum based media, even though it can work effectively in a variety of applications.

 

[Amoo]

Has there been a definitive answer on this debate as to what kind of aluminum these things leach?

 

[Randy Holmes-Farley Verified Community Expert]

Has there been a definitive answer on this debate as to what kind of aluminum these things leach?

No.

 

[FarmerTy]

Your tank represents a neat test for this thread, it would be neat to see what the live rock alone does to maintain your current levels, removing no detritus, for two mos w no other supports. thats the only way to know how much it helps, and i do agree 80lb is a bad boy chunk lol that increases those trace levels. i say do the test, then we'll really know the effects of natural nitrate redux

You're barking up the right tree for experiments... I was a scientist for 10 years before I decided to hang my hat on that career. Sad thing is now I have a ton of money in livestock so experimenting with my tank now is a riskier proposition than it ever was... enough to make me not experiment anymore and just go with what works.

I would say that denitrification is typically incomplete in the majority of reef tanks, thus the many posts lamenting the rise of nitrates.
The main issues are a lack of a contiuous/sufficient food source (carbon) in many tanks for denitrifying bacteria to utilize to breakdown nitrate into nitrogen gas, which then mostly vents into the atmosphere. Another is that the buildup of detritus physically prevents sufficient flow to the aerobic/anerobic coupled bacteria in the substrate, so their efficiency is impaired. And finally, just having a large amount of detritus decomposing in an aquarium adds a constant source of nutrients that can lead to a eutrophic system.

I stir up my LS daily to provide detritus (and it's attached micro-fauna/flora) as a food source for my filter-feeders.

Great information there Nano sapiens and wonderful viewpoint on the micro processes that occur in our tanks!

Detritus is organic matter perhaps also with inorganic matter like calcium carbonate, but that's not important for this question).

Organic matter will be broken down when taken up into bacteria, and some slower degradation will take place just when loose in the water column. Eventually some organic and inorganic matter remains that is largely resistant to further degradation. In the ocean, some of the organic matter has been present for hundreds of years because it is very resistant to biodegradation.

Some nutrients may have a locally higher concentration in detritus if the water flow around it is very low (like in a sand bed or a hole in a rock.

Bits of detritus blowing around in the current are not going to have appreciably high nutrient levels around it because it will rapidly move away by diffusion and convection.

FWIW, I have let a thick mud of detritus accumulate on the bottom of my sumps and refugia, but I'm not trying to keep a ULNS system.

I'm glad I'm not the only one with a thick layer of detritus in the sump.

I'm glad you mentioned marinepure blocks FarmerTy as I was thinking about this study which has already been done:

http://www.cermedia.com/MarinePure Project Report.pdf

FWIW, I have tested my water via Triton and it did show higher Aluminum levels at 82 ug/l, their setpoint being 2 ug/l. My old 125-gallon that went 3 years without water changes did not have a Marine Pure block in it and I never tested the water via Triton on that system. My current 215-gallon has two of them in it, one newly added last week and the other in there since basically it's start. I'm currently at 1.5 years with the system and elevated aluminum levels in it and have yet to see any visual negative effects yet. Time will tell. I plan on testing my water with Triton once a year as a baseline. From what I understand of the testing methods, I'm not going to take their values as absolute but only use them as a comparative baseline to each other to monitor changes annually.

 

[terri_ann]

Very interesting thread guys! I went the Marinepure blocks in all 3 of my sytems. and find that things are better. I always questioned how effective our tanks were with denitrification. I wasn't sold on it being the end-all as it was touted for so many years. FarmerTy, your tank is beautiful!!

 

[brandon429]

I do believe the manmade structures are able to pull it off, but from this thread I also gather that detritus isn't inert/harmless either or the natural designs would be taking care of things alone, without the added cost and support of the retail fixes (except for refugiums or plant binding arrangements). Simply having a plan that removes detritus also saves one from needing any unnatural support means, key tenet, and key inference about the cost of having waste degrade in our systems.

Large tank keepers find it easier to compensate I agree and would likely do as well if I owned any reefs larger than a gallon.

Nobody has piles of detritus where they aren't compensating elsewhere for having left it in, but tons of us use zero compensation other than physical removal of detritus and thats a testament that detritus causes each one of us to take reactive measures, nobody is compiling waste and being action free.


I remember a Toonen study posted last decade 04 ish where he set up dsb tanks with varying degrees of waste, but i don't recall the outcome and even if it showed denitrification as a stat significant outcome, it didn't translate into any practical use for tankers as now we are heading the way of aluminum blocks to compensate heh


The answer to the thread is: the link is strong between nitrates and detritus, it ain't through breaking down yet to minerals so its got some waste to lib.
B