Help with low nitrate & carbon dosing questions

[ReefGeezer]

I think I understand. Not sure. Lol

You say that carbon dosing assists the denitrification process. What I don’t understand as an effect of carbon dosing is how it functions in an environment deprive of an anoxic zone. in other words. If no denitrification exists because most use socks and skimmers to remove organics as well as todays scarcity of porous rock then where is denitrification occurring?

Maybe I'm not capable of understanding the back and forth here but I believe simple carbon dosing as a method is not intended as an aid to the anaerobic denitrification process. It is intended to encourage the growth of bacteria that use organic compounds that include nitrogen and phosphate. I used this method quite a bit until recently. I realized that much of the nitrogen the method binds and removes is ammonia. I don't like that idea as it forces corals to competes with it for the ammonia they need.

 

[Randy Holmes-Farley Verified Community Expert]

I have seen some pretty compelling stuff that dinos in true (hard) coral cannot use no3 at all, but that some hosts can convert it, again, at high energy costs. Some hosts can also recycle building blocks to a degree.

This recent article has a big discussion on nitrate conversion processes on coral reefs, and does not make it sound like nitrate is a poor reservoir of available nitrogen in natural reefs:

Discovery and quantification of anaerobic nitrogen metabolisms among oxygenated tropical Cuban stony corals - The ISME Journal

Coral reef health depends on an intricate relationship among the coral animal, photosynthetic algae, and a complex microbial community. The holobiont can impact the nutrient balance of their hosts amid an otherwise oligotrophic environment, including by cycling physiologically important nitrogen...

www.nature.com

 

[GARRIGA]

Maybe I'm not capable of understanding the back and forth here but I believe simple carbon dosing as a method is not intended as an aid to the anaerobic denitrification process. It is intended to encourage the growth of bacteria that use organic compounds that include nitrogen and phosphate. I used this method quite a bit until recently. I realized that much of the nitrogen the method binds and removes is ammonia. I don't like that idea as it forces corals to competes with it for the ammonia they need.

Heterotrophic bacteria decompose organics in the presence of DO or in its absence with the presence of bound oxygen such as nitrates. Still not clear how adding carbon which is released during decomposition would increase the process of denitrification. Working on it.

 

[Randy Holmes-Farley Verified Community Expert]

Heterotrophic bacteria decompose organics in the presence of DO or in its absence with the presence of bound oxygen such as nitrates. Still not clear how adding carbon which is released during decomposition would increase the process of denitrification. Working on it.

I might suggest reading the article above on the many processes involving nitrate and which organisms do them that I posted above. There's a lot more going on than most reefers assume.

 

[Lasse]

I grasp the need for carbon but wouldn’t that also be released by decomposition of detritus? Best guess being detritus takes longer to break down than expected and why dosing might be needed.

You say that carbon dosing assists the denitrification process. What I don’t understand as an effect of carbon dosing is how it functions in an environment deprive of an anoxic zone. in other words. If no denitrification exists because most use socks and skimmers to remove organics as well as todays scarcity of porous rock then where is denitrification occurring?

You got it - therefore dosing is needed. And it must be DOC (dissolve Organic carbon) - ethanol is the best but other like methanol, suger, vinegar and son on works too.

The whole thing is question of released energy in the metabolic process. O2 provides the most energy for the formation of ATP, NO3 is the next step but provides a much smaller energy supplement for ATP formation - sulphur compounds comes after NO3 in energy exchange.

Many heterotrophic bacteria can switch between O2 and NO3 as electron acceptors while those that can utilize sulphur compounds in the same way are probably all strictly anaerobic. It is the facultative bacteria (facultative = can live both with oxygen and without oxygen) that drive the formation of anaerobic zones. They first consume all the oxygen and then they switch to using NO3 as the electron acceptor.

bound oxygen such as nitrates

Once again it is not the bound oxygen denitrification use - it is the whole NO3 molecule

carbon dosing as a method is not intended as an aid to the anaerobic denitrification process.

Just start to read here Ethanol is the best DOC to use in order to speed up the process
. The aquarists that first introduce the vodka method did not realize that it also speed up the denitrification even if they notice that the PO4 decline fast but NO3 take a month or two before it start to decline

Sincerely Lasse

 

[GARRIGA]

I might suggest reading the article above on the many processes involving nitrate and which organisms do them that I posted above. There's a lot more going on than most reefers assume.

But in general terms, it's widely accepted in the scientific community that heterotrophic bacteria utilize bound oxygen such as found in nitrates when DO is absent. That's all I'm speaking to. As for other mechanisms that might be involved, I'm not questioning or providing any discussion towards that. I'm not educated in them and quite honestly see no point to them so long as I apply what I know correctly.

 

[GARRIGA]

You got it - therefore dosing is needed. And it must be DOC (dissolve Organic carbon) - ethanol is the best but other like methanol, suger, vinegar and son on works too.

The whole thing is question of released energy in the metabolic process. O2 provides the most energy for the formation of ATP, NO3 is the next step but provides a much smaller energy supplement for ATP formation - sulphur compounds comes after NO3 in energy exchange.

Many heterotrophic bacteria can switch between O2 and NO3 as electron acceptors while those that can utilize sulphur compounds in the same way are probably all strictly anaerobic. It is the facultative bacteria (facultative = can live both with oxygen and without oxygen) that drive the formation of anaerobic zones. They first consume all the oxygen and then they switch to using NO3 as the electron acceptor.


Once again it is not the bound oxygen denitrification use - it is the whole NO3 molecule


Just start to read here Ethanol is the best DOC to use in order to speed up the process
. The aquarists that first introduce the vodka method did not realize that it also speed up the denitrification even if they notice that the PO4 decline fast but NO3 take a month or two before it start to decline

Sincerely Lasse

Perhaps we are saying the same thing. My point on bound oxygen being that nitrates contain the oxygen molecule vs it being provided via DO. Fact is, No3 is reduced to No2 then reduced to N in the absence of DO by heterotrophic bacteria. What you are calling faculative is what I generalize as heterotrophic. I'm just an aquarist and not a scientist. This works for me.

However, isn't detritus composed of carbon which is released during decomposition and either utilized directly by heterophic bacterial during decomposition or when released as that detritus breaks down?

 

[ReefGeezer]

I might suggest reading the article above on the many processes involving nitrate and which organisms do them that I posted above. There's a lot more going on than most reefers assume.

Read it and... Yep... Thought so... In over my head again. When you have to google the meaning of every other word, you shouldn't be in the conversation! LOL

Ethanol is the best DOC to use in order to speed up the process. The aquarists that first introduce the vodka method did not realize that it also speed up the denitrification even if they notice that the PO4 decline fast but NO3 take a month or two before it start to decline

Sincerely Lasse

OK... I see where the discussion is going now. Thanks Lasse.

 

[Randy Holmes-Farley Verified Community Expert]

But in general terms, it's widely accepted in the scientific community that heterotrophic bacteria utilize bound oxygen such as found in nitrates when DO is absent. That's all I'm speaking to. As for other mechanisms that might be involved, I'm not questioning or providing any discussion towards that. I'm not educated in them and quite honestly see no point to them so long as I apply what I know correctly.

OK, sure, that's one process. Standard denitrification to produce N2 from nitrate has an equation that looks like this:

organic + 124 NO3– + 124 H+ → 122 CO2 + 70 N2 + 208 H2O

 

[Randy Holmes-Farley Verified Community Expert]

Just start to read here Ethanol is the best DOC to use in order to speed up the process

What is best about ethanol relative to acetate?

 

[Lasse]

in the scientific community that heterotrophic bacteria utilize bound oxygen such as found in nitrates when DO is absent.

Sciences move forwards - that explanation is not valid today - however the explanation and definition I use is valid today. I´m 72 years old - i have read that definition too - in the stone age around 1970, But I´m not so old that I can´t change my opinion

Heterotrophic bacteria can be both facultative or obligate aerobic or anaerobic

However, isn't detritus composed of carbon which is released during decomposition and either utilized directly by heterophic bacterial during decomposition or when released as that detritus breaks down?

Yes you can use the decomposition to produce the DOC needed - I have done it in a recirculated fish farm there we use all organic matter produced by fish and food in serie coupled anaerobic tanks. The first produce DOC like sugar, acetates, alkohols and other DOCs - the next tank did denitrification, But these system was not carbon limited as our aquarium often are. No organic carbon was taken out by mechanical filtration.

What is best about ethanol relative to acetate?

My statement was based on some articles about waste water denitrification I have read - I found this by Google now


I have no access to the whole article for the moment - but I´m sure you have

This can be of interest too

It may be other experiments out there that I´m not aware of that can state different - science change with time

Sincerely Lasse

 

[GARRIGA]

OK, sure, that's one process. Standard denitrification to produce N2 from nitrate has an equation that looks like this:

organic + 124 NO3– + 124 H+ → 122 CO2 + 70 N2 + 208 H2O

That might as well have been in Chinese lol

NO3 to NO2 to N which then escapes into the atmosphere. Works for me

 

[GARRIGA]

Sciences move forwards - that explanation is not valid today - however the explanation and definition I use is valid today. I´m 72 years old - i have read that definition too - in the stone age around 1970, But I´m not so old that I can´t change my opinion

Heterotrophic bacteria can be both facultative or obligate aerobic or anaerobic


Yes you can use the decomposition to produce the DOC needed - I have done it in a recirculated fish farm there we use all organic matter produced by fish and food in serie coupled anaerobic tanks. The first produce DOC like sugar, acetates, alkohols and other DOCs - the next tank did denitrification, But these system was not carbon limited as our aquarium often are. No organic carbon was taken out by mechanical filtration.


My statement was based on some articles about waste water denitrification I have read - I found this by Google now

I have no access to the whole article for the moment - but I´m sure you have

It may be other experiments out there that I´m not aware of that can state different - science change with time

Sincerely Lasse

I’ve read our systems are carbon limited but for those of us not removing organics or doing water changes then it seems carbon dosing only limited to rapid reduction which I’m currently testing. Seems that trapping all detritus isn’t enough.

Test tank has no skimmer or form of mechanical filtration that is then removed. No WC, either.

 

[jda]

This recent article has a big discussion on nitrate conversion processes on coral reefs, and does not make it sound like nitrate is a poor reservoir of available nitrogen in natural reefs:

Discovery and quantification of anaerobic nitrogen metabolisms among oxygenated tropical Cuban stony corals - The ISME Journal

Coral reef health depends on an intricate relationship among the coral animal, photosynthetic algae, and a complex microbial community. The holobiont can impact the nutrient balance of their hosts amid an otherwise oligotrophic environment, including by cycling physiologically important nitrogen...

www.nature.com

I appreciate the link.

I just read the first paragraph since it will take me weeks to read and understand it... but it sounds like the corals that they studied can turn no3 back into ammonium... which is the expensive process that we all knew about, right? I have never implied that no3 cannot be used, only that it is never likely preferred and especially in our tanks when we can make sure to get other forms of nitrogen to our true corals (I have no idea what happens in softies). I imagine that even the super limited amount of no3 in the ocean has to be used if there is no other choice.

From what I understand, ammoni[a,um] is most preferred for nitrogen, bacteria absorption in slime coat is second since the coral can keep nearly all building blocks and energy that it gets from these with very efficient processing, no3 conversion is third and then catching actual food is fourth and can often cost more to capture and process than what is gained. I could be totally wrong since none of these are all studied and written about in one place and you have to piece them together.

 

[Lasse]

I’ve read our systems are carbon limited but for those of us not removing organics or doing water changes then it seems carbon dosing only limited to rapid reduction which I’m currently testing. Seems that trapping all detritus isn’t enough.

Test tank has no skimmer or form of mechanical filtration that is then removed. No WC, either

My tank is nearly the same but I have a skimmer adjusted to max the gas exchange and minimize the foam production. I do not remove any organic and the tank has not get a dissent WC for 4 years. My plan was to build up an organic source below my DSB for denitrification. I have try too do that during 4 years now but I still have to add ethanol into the poor water below my reversed flow under gravel/DSB in order to get a dissent denitrification,

Skiss of my external reversed flow DSB

Sincerely Lasse

 

[jda]

Can I offer another theory about substrate based denitrification that does not involve a carbon source? I have 2-3 inches of sand and lots of real live rock. I add no carbon, but do feed the fish a lot - I buy food by the tens of kilograms. I have to send out ICP to even know what my no3 level is, which is about .1 - the new hannah would likely detect this. I talked with Dr. Ron a bunch about this and thought that there was a hole in his DSB theory which allowed too much inert sludge into the DSB that gums up the works - he was intrigued and did not have an answer for my question about what happens to the fully-broken down organics. About every 3-4 years, I vacuum small sections of my sandbed at a time down to the bottom. I take a year to do this with all of the accessible areas. When you see the microfauna and life all head to those freshly vacuumed areas, it is easy to see that something was happening over time down there that they do not prefer - some surely from the die off of the disturbing, but they stay there until I vacuum more well beyond what some die off could supply. I believe that anybody who wants the sand to denitrify needs to remove the inert grey sludge from the sand occasionally... like 4 years seems about right to me.

Basically, the inert gunk gums up the works and does not allow stuff to move through there that well. Perhaps the semi-pleneum in the photo above works to keep the gunk out too.

FWIW - I also keep my po4 about 1-3 ppb, which happens naturally with at least three skimmers on each tank and a fuge. Whether I vacuum sand, or not, the sand does not become a po4 reservoir nor a "time bomb."

 

[GARRIGA]

My tank is nearly the same but I have a skimmer adjusted to max the gas exchange and minimize the foam production. I do not remove any organic and the tank has not get a dissent WC for 4 years. My plan was to build up an organic source below my DSB for denitrification. I have try too do that during 4 years now but I still have to add ethanol into the poor water below my reversed flow under gravel/DSB in order to get a dissent denitrification,

Skiss of my external reversed flow DSB

Sincerely Lasse

Have you tried reducing the flow through the UG filter? I’ve been playing with flow and have confirmed that I’m more efficient at reducing both nitrates and phosphates at the bottom end yet can utilize carbon dosing at max.

In the 80s had a salt tank with an UG filter and without WC kept nitrates around 20 ppm. No algae yet used lights that sustained my very large purple tip sabae anemone. In the 90s ran another with a canister where nitrates got over 80 but overtime dropped to 20 ppm and I concluded was due to the reduced flow from the canister clogging with detritus. No WC either. No algae problems either.

I was young and had no time for proper maintenance plus was constantly out and about. Yet understood denitrification required a slow flow and just assumed that’s what I had inadvertently created.

I hate WCs. Hate carrying buckets. Want to sit back and enjoy the show. Good thing carbon dosing can be automated with a dozer but would be nice to have a filter that resolved all of it.

 

[Lasse]

Have you tried reducing the flow through the UG filter? I’ve been playing with flow and have confirmed that I’m more efficient at reducing both nitrates and phosphates at the bottom end yet can utilize carbon dosing at max.

I manage both the flow and the injection of DOC with help of a Profilux 4 and a redox probe. i´ll try to have the redox around minus 190 mV.

Sincerely Lasse

 

[GARRIGA]

I manage both the flow and the injection of DOC with help of a Profilux 4 and a redox probe. i´ll try to have the redox around minus 190 mV.

Sincerely Lasse

That’s interesting. Learned about redox in early to mid 90s used with the Berlin Method and ozone but
seemed too complex for me to execute and was concerned with the potential issues. Have considered getting a probe from HM Digital to monitor the health of the filtration. You’ve now reminded me that’s probably what I’m missing to monitor the progress of my tests.

Have you noticed the redox improving as you reduce flow? My assumption has been that we run too much water through our filtration and can provide adequate flow through the DT more effectively via wave pumps and obtain better filtration by separating filter turnover from tank turnover.

GHL on my short list for my upcoming DT although that’s still a couple of years away and who knows what will be available then. Definitely have no desire to keep doing manual testing as I get older. Rather go fishing and four wheeling and just sit back and enjoy my piece of the ocean.

BTW, are you also using ozone or just reading redux?

 

[Lasse]

BTW, are you also using ozone or just reading redux?

I use one probe in order to control the anaerobic condition. It is constructed that way that if the flow rise - the amount of DOC will rise as well - keeping the ORP at the same level. If the flow decline - injection of DOC decline.

I also use redox to monitoring my DT - mostly because I use an Oxidator. Do not use Ozone.

Sincerely Lasse