Help with low nitrate & carbon dosing questions

[Mr. GoodStuff]

In need of some information regarding nitrates and phosphates. So about a month ago I tested my tank parameters and found phosphates out of whack at 0.77ppm (February 3rd) and had to make some changes; so I've done some water changes and setup a GFO reactor. Fast forward about a month and I managed to slowly lower the phosphates down to 0.19ppm (March 10th), still a bit higher than I'd like but we're getting there and I probably have to change GFO media.

However I also decided to check nitrate levels and found them to be at 0 for several days straight. Upped my feeding slightly and added a bit more phyto than usual to try and get nitrates up a bit with no luck, still 0. So I went and purchased Brightwell NeoNitro and added the recommend amount based on water volume to achieve 2ppm nitrates but after testing again I'm at 0. After reading the bottle it explains tank may be carbon limited and in that case to use Brightwell Bio Fuel or in other words carbon dosing.

Now the part I'm confused about is when I research carbon dosing whether with off the shelf products or DIY it appears to be a method to lower nitrates and phosphates. NeoNitro is to raise nitrates but I need to add Bio Fuel in order for it to work but Bio Fuel is supposed to lower nitrates? What am I missing here or not understanding?

What should be my course of action? I'm not running a skimmer or refugium at the moment, would that help?

 

[nereefpat]

Carbon dosing is, primarily, used for decreasing nitrate. I don't think that's the situation you're in.

Using small amounts of GFO to slowly decrease P to where you want it is a great plan, so I'd just keep doing that. As for nitrate, as long as you are feeding your fish I wouldn't sweat the nitrate value. I think you seem to be doing things right.

So I went and purchased Brightwell NeoNitro and added the recommend amount based on water volume to achieve 2ppm nitrates but after testing again I'm at 0. After reading the bottle it explains tank may be carbon limited and in that case to use Brightwell Bio Fuel or in other words carbon dosing.

Now the part I'm confused about is when I research carbon dosing whether with off the shelf products or DIY it appears to be a method to lower nitrates and phosphates. NeoNitro is to raise nitrates but I need to add Bio Fuel in order for it to work but Bio Fuel is supposed to lower nitrates? What am I missing here or not understanding?

I think reading the labels on supplements is confusing you. I would just keep doing what you're doing, with GFO and feeding.

Is this a reef? Are you having algae issues, or coral issues? Chasing values is kind of a different game to play, in my experience.

Edit: difficult game to play

 

[Mr. GoodStuff]

Carbon dosing is, primarily, used for decreasing nitrate. I don't think that's the situation you're in.

Using small amounts of GFO to slowly decrease P to where you want it is a great plan, so I'd just keep doing that. As for nitrate, as long as you are feeding your fish I wouldn't sweat the nitrate value. I think you seem to be doing things right.


I think reading the labels on supplements is confusing you. I would just keep doing what you're doing, with GFO and feeding.

Is this a reef? Are you having algae issues, or coral issues? Chasing values is kind of a different game to play, in my experience.

Yeah it's a reef and I'm not having any issues with fish or coral, just was under the impression that having 0 nitrates long term usually isn't good and wanted to prevent that from happening.

 

[minus9]

Use PNS Probio combined with PNS Yello Sno and your problem will be taken care of. Probio will lower your PO4 and not deplete NO3 and YS will feed your corals some much needed nitrogen. I had a similar situation and this combo did the job. How to dose PNS

 

[Mr. GoodStuff]

I'm starting to think my nitrate test kit is bad... I took a sample of my tank water and I added about 10-15 drops of neonitro into the sample and then added the API test solution, still showed 0. Maybe that's normal but I'm assuming it should show rather high if I just added neonitro to it.

 

[GARRIGA]

Heterotrophic bacteria require food to utilize bound oxygen in the form of nitrates in an anoxic environment which is rich in bound oxygen but devoid of DO. All life forms require phosphates including these heterotrophic bacteria. That’s might explain the recommendation to not only add nitrates but also add carbon (the food source).

As for needing nitrates. That’s always contradicted my understanding of how most plants and algae utilize nitrogen. My understanding being they prefer ammonium and have to down convert nitrates to nitrites then ammonium in order to utilize it. I wonder if those having issues from low nitrates tend to underfed their systems and why there’s an issue. Not lack of nitrates but lack of ammonium added.

Have noticed a few mentioning this and this makes more sense. The Redfield Ratio being based on nitrogen and phosphorus and perhaps the reef community anecdotally transcribed that to nitrates and phosphates since those are two value we can test and nitrates best match nitrogen as far as wording.

Do know this. Only way for me to lower nitrates is by raising my phosphates. Definite correlation I’ve experienced but could it be just that I came closer overall to the C:N ratios of 100:16:1? Beyond my peanut brain’s ability to fully comprehend.

 

[minus9]

I'm starting to think my nitrate test kit is bad... I took a sample of my tank water and I added about 10-15 drops of neonitro into the sample and then added the API test solution, still showed 0. Maybe that's normal but I'm assuming it should show rather high if I just added neonitro to it.

Well, if you're using API test kits, then yes, they absolutely stink!

 

[minus9]

Heterotrophic bacteria require food to utilize bound oxygen in the form of nitrates in an anoxic environment which is rich in bound oxygen but devoid of DO. All life forms require phosphates including these heterotrophic bacteria. That’s might explain the recommendation to not only add nitrates but also add carbon (the food source).

As for needing nitrates. That’s always contradicted my understanding of how most plants and algae utilize nitrogen. My understanding being they prefer ammonium and have to down convert nitrates to nitrites then ammonium in order to utilize it. I wonder if those having issues from low nitrates tend to underfed their systems and why there’s an issue. Not lack of nitrates but lack of ammonium added.

Have noticed a few mentioning this and this makes more sense. The Redfield Ratio being based on nitrogen and phosphorus and perhaps the reef community anecdotally transcribed that to nitrates and phosphates since those are two value we can test and nitrates best match nitrogen as far as wording.

Do know this. Only way for me to lower nitrates is by raising my phosphates. Definite correlation I’ve experienced but could it be just that I came closer overall to the C:N ratios of 100:16:1? Beyond my peanut brain’s ability to fully comprehend.

Yes, the easiest way to introduce nitrogen is feeding your fish multiple times a day, not just one cube of mysis (which seems to be the common method around here), but that cube broken up over the course of the day, combined with quality flakes and pellets. I prefer a better frozen food over mysis, LRS or Rod's. I never understood why so many reefers latched onto this whole notion of the Redfield ratio being something to shoot for in our tanks? It has absolutely nothing to do with how corals utilize nutrients, especially in our tanks. I think you have to look at nutrients based on your PO4 levels and target a range of NO3, but honestly, if you have the slightest measurement of NO3, you're fine. It's this rollercaoster ride people take with nutrients that causes so many problems. If there's algae growing in your tank, then there's plenty of nitrogen available, it's just being utilized by other forms.

 

[GARRIGA]

Yes, the easiest way to introduce nitrogen is feeding your fish multiple times a day, not just one cube of mysis (which seems to be the common method around here), but that cube broken up over the course of the day, combined with quality flakes and pellets. I prefer a better frozen food over mysis, LRS or Rod's. I never understood why so many reefers latched onto this whole notion of the Redfield ratio being something to shoot for in our tanks? It has absolutely nothing to do with how corals utilize nutrients, especially in our tanks. I think you have to look at nutrients based on your PO4 levels and target a range of NO3, but honestly, if you have the slightest measurement of NO3, you're fine. It's this rollercaoster ride people take with nutrients that causes so many problems. If there's algae growing in your tank, then there's plenty of nitrogen available, it's just being utilized by other forms.

I'm theorizing that if we fed our tanks multiple times per day and showed zero nutrients then the corals would still have been fed. Notice many claiming they can't raise their nutrients yet their tanks are just fine. Really curious if those having issue with low nutrients are mostly those who starve their tanks relative to amount of filtration provided. Fact fish produce ammonia throughout the day leads me to believe that corals will find enough nitrogen to meet the needs of their zooxanthellae. Same with phosphates.

 

[Subsea]

Corals have redundant nitrogen management techniques aside from zooanthelia conversions of inorganic nutrients into glucose during photosynthesis. Cynobacteria living in coral biomass do that.

https://www.amnh.org/explore/news-blogs/research-posts/corals-nitrogen-microbes

[Because nitrogen-fixing microbes could be an additional source of nitrogen for corals, they are thought to play an important role in coral health and physiology. The general expectation is that when dissolved nitrogen levels are low in the water, corals might get more nitrogen from nitrogen-fixing microbes, with the opposite occurring when there is a high level of biologically available nitrogen. ]

PS: I dose ammonia to reduce phosphate.

 

[Lasse]

Many contradicting advises here - here is one more - just in order to make you more confused

IMO - if your measurements are right - you are depleted in nitrogen - one of the reasons why your phosphates hit the sky. There is not enough of nitrogen in your aquarium water for a healthy growth of algae, bacteria and corals. Food contain natural ratios of P and N. If you go the path with feeding more - you will also rise the input of P. The trick here is to - IMO - introduce N in the aquarium without adding any P. You can do it by adding NH4 (ammonia ions) or NO3 (nitrates). Most organisms can use either but it is most costly to use NO3 (according to energy input from the organism). Hence - NH4 (ammonia ions) seems to be the perfect way of dosing - but - it is always a but - it is more dangerous to add NH4 because if it form residues (not directly uptake) some of it will be converted to the toxic NH3 (ammonia gas). This process is mainly pH and temperature depended. With dosing NO3 - the risk for NH3 spikes is more or less zero. However - both compounds is very difficult to measure - our tests is normally not good enough. Therefore - try to measure - at least NO3 with more than one method. The normal NO3 test I prefer is the NO2/NO3 test from Fauna Marine and the NO2/NO3 pro test from Tropic Marine. They give your a possibility to compensate for nitrite in the water. Because that my eyes is not the best - I use Hanna Low Nitrate checker but with caution.

If you have near zero in nitrate - you should (IMO) not use any extra DOC (Dissolved Organic Carbon)

For the book - this below is not true nowadays

Heterotrophic bacteria require food to utilize bound oxygen in the form of nitrates in an anoxic environment which is rich in bound oxygen but devoid of DO

In fact - IMO - they use the whole molecule (NO3) in the same place in the process there they use O2 if dissolved Oxygen is present. With DO in the water - Oxygen is the electron acceptor and CO2 is the waste. If not Oxygen is available - but there is NO3 - NO3 will act as electron acceptor and NO2/N2 gas is the waste. If not O2 and NO3 is available - different sulphur compounds is used the same way and hydrogen sulphide is the wast. And so on down to CO2 that is the last thinkable electron acceptor. The reason for this down going spiral is that using O2 - give a high energy input, NO3 much lower, Sulphur compounds lower the energy gain more and so on

I'm theorizing that if we fed our tanks multiple times per day and showed zero nutrients then the corals would still have been fed. Notice many claiming they can't raise their nutrients yet their tanks are just fine. Really curious if those having issue with low nutrients are mostly those who starve their tanks relative to amount of filtration provided. Fact fish produce ammonia throughout the day leads me to believe that corals will find enough nitrogen to meet the needs of their zooxanthellae. Same with phosphates.

This is not any mystery at all. What we measure in our tanks is the left over - the nutrient that not have been used. The nutrient the organism use is the nutrient we put in - the flux of nutrient so to say. If we measure 0 of different nutrients - we do not know if we have enough high flux of nutrients into the system - but if we measure a small concentration of leftover - we know that the flux is enough. Image that I have to fill up a cup of coffee all the way - but in a dark room. I need to know exactly when it spill over - but I can´s see when it is totally filled. If I place the cup on a plate - hold the plate in my hand with the thumb on the lowest part of the upside of the plate - I know that when the thumb get warm and wet - i have filled the cup enough - even when I cant´s see the level.

Sincerely Lasse

 

[GARRIGA]

In fact - IMO - they use the whole molecule (NO3) in the same place in the process there they use O2 if dissolved Oxygen is present. With DO in the water - Oxygen is the electron acceptor and CO2 is the waste. If not Oxygen is available - but there is NO3 - NO3 will act as electron acceptor and NO2/N2 gas is the waste. If not O2 and NO3 is available - different sulphur compounds is used the same way and hydrogen sulphide is the wast. And so on down to CO2 that is the last thinkable electron acceptor. The reason for this down going spiral is that using O2 - give a high energy input, NO3 much lower, Sulphur compounds lower the energy gain more and so on

Are you saying denitrification doesn't require the absence of DO? Please point me to the literature supporting this as fact. Everything I've read since the 70s indicates heterotrophic bacteria need the absence of DO oxygen in order to utilize bound oxygen in the form of nitrates and sulphates to break down a carbon source such as detritus. I'm always open to learning something new yet find myself able to eliminate nitrates in the absence of carbon dosing by reducing flow and creating an anoxic zone. In the absence of that, have not been able to reduce nitrates outside of using carbon dosing such as NoPox which I started using recently. I'm old school but getting around to trying new ideas even if they aren't exactly new.

 

[GARRIGA]

This is not any mystery at all. What we measure in our tanks is the left over - the nutrient that not have been used. The nutrient the organism use is the nutrient we put in - the flux of nutrient so to say. If we measure 0 of different nutrients - we do not know if we have enough high flux of nutrients into the system - but if we measure a small concentration of leftover - we know that the flux is enough. Image that I have to fill up a cup of coffee all the way - but in a dark room. I need to know exactly when it spill over - but I can´s see when it is totally filled. If I place the cup on a plate - hold the plate in my hand with the thumb on the lowest part of the upside of the plate - I know that when the thumb get warm and wet - i have filled the cup enough - even when I cant´s see the level.

Sincerely Lasse

I'm just speculating on what details surround those with low nutrients and issues supposedly caused by it. Perhaps those are under feeding (since there is this mantra about not feeding to keep nutrients low) as far back as I can remember with corals. As early as the 90s yet I see some who have transitioned away from that belief because we have since learned ultra low isn't healthy yet I'm not sure the change in feeding behavior has changed as well.

I'm well aware of what we are measuring. That's never been a mystery to me.

 

[ReefGeezer]

...Now the part I'm confused about is when I research carbon dosing whether with off the shelf products or DIY it appears to be a method to lower nitrates and phosphates. NeoNitro is to raise nitrates but I need to add Bio Fuel in order for it to work but Bio Fuel is supposed to lower nitrates? What am I missing here or not understanding?

What should be my course of action? I'm not running a skimmer or refugium at the moment, would that help?

A lot of marketing goes into the instructions on these products.
1. None of these products are required. Simple DIY carbon dosing work just as well; but
2. Carbon dosing requires both nitrogen and phosphate to work;
3. Carbon dosing lowers nitrates much faster than phosphates, and...
4. Once nitrates are 0, the process stops.

Yes, you could dose nitrates to help the carbon dosing process keep working. You will find that it takes a boat load more of the NeoNitro to raise and maintain nitrate levels than the instructions say. Increasing feeding to increase nitrate is a fine Idea, except that it may also increase phosphates and probably won't make nitrates rise high enough or fast enough to help. Really, Carbon dosing is not a suitable method when the goal is to reduce high levels of phosphate in a low nitrate environment.

GFO or dosing Lanthanum Chloride might be better alternatives because they bind the phosphate without using nitrate. Both of these have strengths and weaknesses. There is also some risks involved. Go slow, read a lot, and ask questions before starting.

 

[jda]

Go back to the basics. Understand nitrogen, not nitrate. Your corals need nitrogen, not nitrate. If you are feeding a bunch, then they are getting it from ammonia/ammonium in available form and are totally fine.

Nitrate is a residual measurement of what is left over. Easy to test, east to misunderstand, but not great for most corals since they have to convert it to use it at a great energy cost that nobody really knows, but estimated at 30-60%. Can be great for macro algae and even poisoning dinos, cyano and diatoms at higher levels.

Available > residual.

 

[Lasse]

Are you saying denitrification doesn't require the absence of DO? Please point me to the literature supporting this as fact. Everything I've read since the 70s indicates heterotrophic bacteria need the absence of DO oxygen in order to utilize bound oxygen in the form of nitrates and sulphates to break down a carbon source such as detritus. I'm always open to learning something new yet find myself able to eliminate nitrates in the absence of carbon dosing by reducing flow and creating an anoxic zone. In the absence of that, have not been able to reduce nitrates outside of using carbon dosing such as NoPox which I started using recently. I'm old school but getting around to trying new ideas even if they aren't exactly new.

Yes - denitrification needs the absence of DO and presence of NO3,

What I´m saying is that the part I have marked bold and cursive is not true - especially to utilize bound oxygen. In aerobic conditions (presence of DO) - oxygen gas (O2) is the final electron acceptor electron transport chain - in anaerobic conditions (absence of DO) different other molecules like NO3 serve as the final electron acceptor in the same chain. It is not the way that the organism try to extract bound Oxygen - it is the whole molecule that will do what O2 does in aerobic conditions. Read here

The dosing of DOC (dissolved Organic Carbon like ethanol, suger and so on) in order to speed up denitrification has two major reasons.

1. To give C as a building block for bacteria growth
2. it serve as an electron donor in the electron transport chain and this is IMO the most important role it has in denitrification.

Sincerely Lasse

 

[Lasse]

since they have to convert it to use it at a great energy cost that nobody really knows, but estimated at 30-60%. Can be great for macro algae and even poisoning dinos, cyano and diatoms at higher levels.

Its the same energy cost for all photosynthetic organism which are able to use NO3 as a nitrogen source. Some of the microalgae can not even use NO3 as an N source - it is well-known in freshwater there NO3 is used as fertilizer instead of NH4 (ammonium ions) just in order not to promote algae growth - in spite of the fact that it will give 30 - 60 % lesser growth

Sincerely Lasse

 

[GARRIGA]

Yes - denitrification needs the absence of DO and presence of NO3,

What I´m saying is that the part I have marked bold and cursive is not true - especially to utilize bound oxygen. In aerobic conditions (presence of DO) - oxygen gas (O2) is the final electron acceptor electron transport chain - in anaerobic conditions (absence of DO) different other molecules like NO3 serve as the final electron acceptor in the same chain. It is not the way that the organism try to extract bound Oxygen - it is the whole molecule that will do what O2 does in aerobic conditions. Read here

The dosing of DOC (dissolved Organic Carbon like ethanol, suger and so on) in order to speed up denitrification has two major reasons.

1. To give C as a building block for bacteria growth
2. it serve as an electron donor in the electron transport chain and this is IMO the most important role it has in denitrification.

Sincerely Lasse

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?

I have an experimental tank with a large area of porous pumice under slow flow that acts as my anoxic zone. No skimmer. No socks. No water changes. Everything is left to decompose and get processed. As proof of the process working. I often purposely raise my nitrates then overdose carbon to test the affects. Add MB7 and water gets slightly cloudy for a couple of days then clears up. No signs of oxygen deprivation. Best assumption is there’s such a large surface area for bacteria they eventually settle in and quickly utilize the new carbon and existing nitrates. If I stop over feeding then nitrates remain under 5 ppm assuming I add phosphates if those get depleted. Seems Redfield explains that although I’ve found it may not be an exact 10:1 ratio although nitrites might be throwing my numbers off.

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.

Carbon dosing is one of those areas where I know it works. I have an understanding of how it works yet at a cross road of exactly how it works in tanks where little denitrification could occur.

You may have explained and just failed to grasp it. What I do understand is that denitrification can not occur in the presence of DO. I think that’s also what you said but not sure. Lol

 

[jda]

Its the same energy cost for all photosynthetic organism which are able to use NO3 as a nitrogen source. Some of the microalgae can not even use NO3 as an N source - it is well-known in freshwater there NO3 is used as fertilizer instead of NH4 (ammonium ions) just in order not to promote algae growth - in spite of the fact that it will give 30 - 60 % lesser growth

Sincerely Lasse

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.

Seems anecdotally likely to me that corals not operating at 100% probably cannot withstand this for long... and even corals at 100% might not stay there indefinitely needing to expel this type of energy. Also, even in the presence of higher residual no3 levels, most healthy coral probably are using ammonium anyway.

I have always been amazed that people will turn their noses as dosing ammoina/ammonium since they are so conditioned to be wary of it from the initial cycle, yet they will put stump remover or other black box supplements in their tanks without question.

 

[GARRIGA]

Considering plants do tend to prefer ammonium and have to down concert nitrates to ammonium before being utilized, I’m also from the camp that algae do the same. Micro, macro and very likely zooxanthella.