Ammonium dosing is a bit overrated

[Randy Holmes-Farley]

I understand that another nutrient could be limiting, but how does having nitrate and phosphate in a certain proportion to each other relate to iron solubility and availability?

I don’t think that’s the issue he was addressing, as opposed to merely having lots of N and P in any ratio does not necessarily imply algae growth if iron is limiting.

 

[Hans-Werner]

I understand that another nutrient could be limiting, but how does having nitrate and phosphate in a certain proportion to each other relate to iron solubility and availability?

Nitrate is a strong oxidant and can keep iron oxidized in the substrate, in the interstitial water of the substrate to be more precise. The nitrate is used as electron acceptor before iron is reduced from Fe3+ to Fe2+. Even if iron is reduced deeper in the substrate at night it can get re-oxidized by nitrate near the substrate's surface.

Phosphate could also limit soluble iron by simply precipitating iron(III) phosphate as we know it from GFO.

Proportion is not important in my opinion but could be just an empirical number. Let's say we try to keep phosphate at 0.05 ppm the resulting nitrate concentration could be 2.5 ppm (50 times, Delbeek) or 5 ppm (100 times, Fauna Marin). Maybe these are reasonable nitrate concentrations to keep iron oxidized, I don't know. I don't use or handle such ratios.

I don't think these nitrate concentrations are necessary or especially useful as a nutrient. In my eyes "nutrient" is a bad explanation for these ratios. They just don't make sense as nutrient ratios for dissolved nutrients. External concentrations and uptake dynamics at certain external concentrations and internal N to P ratios inside the organisms are two completely different things, and it is completely impossible to conclude from one onto the other, at least not in the volumes and concentrations we have in reef tanks.

 

[Randy Holmes-Farley]

Nitrate is a strong oxidant and can keep iron oxidized in the substrate, in the interstitial water of the substrate to be more precise. The nitrate is used as electron acceptor before iron is reduced from Fe3+ to Fe2+. Even if iron is reduced deeper in the substrate at night it can get re-oxidized by nitrate near the substrate's surface.

Phosphate could also limit soluble iron by simply precipitating iron(III) phosphate as we know it from GFO.

Proportion is not important in my opinion but could be just an empirical number. Let's say we try to keep phosphate at 0.05 ppm the resulting nitrate concentration could be 2.5 ppm (50 times, Delbeek) or 5 ppm (100 times, Fauna Marin). Maybe these are reasonable nitrate concentrations to keep iron oxidized, I don't know. I don't use or handle such ratios.

I don't think these nitrate concentrations are necessary or especially useful as a nutrient. In my eyes "nutrient" is a bad explanation for these ratios. They just don't make sense as nutrient ratios for dissolved nutrients. External concentrations and uptake dynamics at certain external concentrations and internal N to P ratios inside the organisms are two completely different things, and it is completely impossible to conclude from one onto the other, at least not in the volumes and concentrations we have in reef tanks.

Unless bacteria or something else catalyze it, I’m not convinced the reaction between nitrate and ferrous iron is fast enough to be important. There’s no reason to think it faster than air oxidation of ferrous iron.

 

[Stamboli]

(100 times, Fauna Marin)

According to Fauna Marin this recommended ratio is the result of thousands of ICP analyses by the company. Supposedly there is a correlation between well running tanks and this 100:1 ratio.

 

[Randy Holmes-Farley]

According to Fauna Marin this recommended ratio is the result of thousands of ICP analyses by the company. Supposedly there is a correlation between well running tanks and this 100:1 ratio.

I dont have reason to believe they have a good understanding of chemistry, but that aside, my recommended ranges certainly include that ratio, but I also give limits to both. A simple ratio does not either give absolute limits nor does it say how far one must deviate from that ratio before things are less desirable.

It’s like saying your optimal weight for your height is 170 pounds. So is 169 bad? 160? 150?? Etc

 

[Stamboli]

my recommended ranges certainly include that ratio, but I also give limits to both

Fauna Marin only says that the best tanks they have seen and analyzed were close to this 100:1 ratio. But I think you're right that it don't have to.

In my own tank everything was fine with the 100:1 ratio. And when nitrate has dropped and the ratio was 50:1, it still was fine. But when nitrate has dropped to zero and phosphate was 0.1, the good days were over.

So I would just say that tank water should have more nitrate than phosphate. By the way the same in nature reefs: Nitrate about 0,1 – 1,0 µM / Phosphate 0,05 – 0,2 µM (Muscatine et al., 1981; Dubinsky & Stambler, 2011)

 

[Hans-Werner]

Fauna Marin only says that the best tanks they have seen and analyzed were close to this 100:1 ratio. But I think you're right that it don't have to.

In my own tank everything was fine with the 100:1 ratio. And when nitrate has dropped and the ratio was 50:1, it still was fine. But when nitrate has dropped to zero and phosphate was 0.1, the good days were over.

So I would just say that tank water should have more nitrate than phosphate. By the way the same in nature reefs: Nitrate about 0,1 – 1,0 µM / Phosphate 0,05 – 0,2 µM (Muscatine et al., 1981; Dubinsky & Stambler, 2011)

Can you please name the title of the 2011 publication?

This would be 0.006 to 0.06 mg/l nitrate and 0.005 to 0.02 mg/l phosphate. I don't think these are the numbers we are just talking about. If we expect both nutrients to rise in a similar ratio in environments rich or poor in nutrients, we stay in the same order of magnitude for both concentrations and not two orders of magnitude apart.

 

[Hans-Werner]

Unless bacteria or something else catalyze it, I’m not convinced the reaction between nitrate and ferrous iron is fast enough to be important. There’s no reason to think it faster than air oxidation of ferrous iron.

At least there are some hints from scientific literature, bacteria are involved:

https://www.sciencedirect.com/science/article/abs/pii/S0012821X16305052

https://journals.asm.org/doi/full/10.1128/aem.01570-16

https://journals.asm.org/doi/full/10.1128/aem.00743-13

Just a few of the hits.

 

[Stamboli]

Can you please name the title of the 2011 publication?

I would like to, but my information was the result of copy & paste. Maybe the figures are not accurate, there are many different figures regarding nitrate and phosphate levels in natural coral reefs. But I don't think that's very important for us. We only need to know what works well in our coral reefs.

By the way, I just visited the Fauna Marin website because I wanted to know what they actually recommend. Here it is:

Total Phosphate : Nitrate = 1:100

This refers to the ratio of phosphate to nitrate. You can also measure this value regularly at home. The individual values themselves are not important for this factor; it's only important that this ratio is maintained as closely as possible.

It's important to keep the PO₄³⁻ stable and make changes slowly and over several days or weeks. The nitrate value must always be higher than the PO₄³⁻ value, and the nitrate value is significantly less important than the PO₄³⁻ value. Therefore, the tendency towards change must always be regulated downwards. However, you should ensure that this does not lead to a limitation.

Wissensdatenbank - Fauna Marin

www.faunamarin.de

 

[Hans-Werner]

I would like to, but my information was the result of copy & paste. Maybe the figures are not accurate, there are many different figures regarding nitrate and phosphate levels in natural coral reefs. But I don't think that's very important for us. We only need to know what works well in our coral reefs.

By the way, I just visited the Fauna Marin website because I wanted to know what they actually recommend. Here it is:

Total Phosphate : Nitrate = 1:100

This refers to the ratio of phosphate to nitrate. You can also measure this value regularly at home. The individual values themselves are not important for this factor; it's only important that this ratio is maintained as closely as possible.

It's important to keep the PO₄³⁻ stable and make changes slowly and over several days or weeks. The nitrate value must always be higher than the PO₄³⁻ value, and the nitrate value is significantly less important than the PO₄³⁻ value. Therefore, the tendency towards change must always be regulated downwards. However, you should ensure that this does not lead to a limitation.

Wissensdatenbank - Fauna Marin

www.faunamarin.de

I think the figures are accurate. I have collected some of these data for my own lectures. Likely I have the cited article somewhere, but I just wanted to check quickly. The ratios scientific articles give for N and P are shown in the slides from one of my lectures.

How important is this ratio of 1:100 or 1:50? I myself and other reefers are successfull far outside of these ratios.

Like I said, science clearly says it has nothing to do with nitrate as a nutrient, because at these ratios the concentrations of nitrate with reasonable phosphate concentrations exceed the saturation concentrations for this nutrient, nitrate.

 

[Stamboli]

How important is this ratio of 1:100 or 1:50? I myself and other reefers are successfull far outside of these ratios.

Have you also seen successful reef tanks with a reverse ratio of 10:1 (phosphate to nitrate) for example?

 

[Featherweight]

100% anecdotal but in my 250 I had little patches of sand dwelling dinos start popping up and when tested my nitrate was 0 and phosphate was like .2 or .4. I don't recall exacts on PO4. This caught me off guard because my 250 routinely ran high nitrates for months and months.

I started dosing ammonia according to Randy's thread and almost overnight the dino patches were smothered in cyano and then disappeared shortly after.

I think I put pics in Randy's thread to document it all but don't remember

I am going through this now. Po4 testing between .08 and .12. nitrates testing between 0 and 1 on Hannah checkers. Dino coming and going, not as bad as the last time I fought em off, but certainly there.

 

[areefer01]

I would like to, but my information was the result of copy & paste. Maybe the figures are not accurate, there are many different figures regarding nitrate and phosphate levels in natural coral reefs. But I don't think that's very important for us. We only need to know what works well in our coral reefs.

By the way, I just visited the Fauna Marin website because I wanted to know what they actually recommend. Here it is:

Total Phosphate : Nitrate = 1:100

This refers to the ratio of phosphate to nitrate. You can also measure this value regularly at home. The individual values themselves are not important for this factor; it's only important that this ratio is maintained as closely as possible.

It's important to keep the PO₄³⁻ stable and make changes slowly and over several days or weeks. The nitrate value must always be higher than the PO₄³⁻ value, and the nitrate value is significantly less important than the PO₄³⁻ value. Therefore, the tendency towards change must always be regulated downwards. However, you should ensure that this does not lead to a limitation.

Wissensdatenbank - Fauna Marin

www.faunamarin.de

The discussion has turned a bit but if I remember Delbeek's December talk he pointed out that Fauna Marin has it backwards. He reached out to them to let them know. FM has PO4/NO3 and it should be the other way. If you look at Delbeek's talk he discusses this around the 16:00 minute marker.

 

[Featherweight]

That’s why I made this thread!

…that’s also why I ended up making this chart. It’s very easy; if nitrate is undetectable and doesn’t increase by the third day of ammonia dosing, skip to the following week’s dose.

Here’s the thread with the full instructions. It’s mainly about when to use dosing pumps, how to progress the chart, as well as other fun ammonia facts.

DIY Ammonia Dosing Chart

Introduction: Many reef tanks have an incredible nitrate demand, and despite the additional fish and coral food, still struggle to make an impact on the nitrate level. This can subject corals, anemones, coralline, macro/microalgae, and clams to nutrient starvation. Any photosynthetic organism...

www.reef2reef.com

Dayum. I felt like I was dumping in my ammonia solution at 30 ml per day on around 160g water volume. I'm just starting to break through...

 

[Featherweight]

I went with Tropic Marin Amino-Organic for the N and Phos-Feed for the P. My N was reading 0ppm. Corals looked good, regained color from ODing ammonium but algae was nuts! I was adding snails trying to keep up. I got fed up and went back to ammonium bicarbonate and urea and Phos-Feed for the P (I like the Phos-Feed). This morning my N was 8ppm and my P was 0.264. Algae growth is almost non existent, very slow and corals are fat and happy.

Yup, getting undesirable algea w 0 to 1 nitrate and 0.1 phosphates

 

[BriDroid]

Yup, getting undesirable algea w 0 to 1 nitrate and 0.1 phosphates

I am really happy dosing the ammonium bicarbonate/urea mixture. It's working extremely well for me so far (corals have good color, NO3 is measurable, and I'm not dosing a ton of it just to keep the NO3 measurable). I know that molar ratio doesn't mean much, but like I said above it is working for me and the algae growth is really slow, so I'm going to continue following it

 

[Randy Holmes-Farley]

Total Phosphate : Nitrate = 1:100

This refers to the ratio of phosphate to nitrate. You can also measure this value regularly at home. The individual values themselves are not important for this factor; it's only important that this ratio is maintained as closely as possible.

Imo, that isn’t sensible in the least.

It means that 1,000 ppm phosphate and 100,000 ppm nitrate is a good set of values.

 

[rishma]

I would like to, but my information was the result of copy & paste. Maybe the figures are not accurate, there are many different figures regarding nitrate and phosphate levels in natural coral reefs. But I don't think that's very important for us. We only need to know what works well in our coral reefs.

By the way, I just visited the Fauna Marin website because I wanted to know what they actually recommend. Here it is:

Total Phosphate : Nitrate = 1:100

This refers to the ratio of phosphate to nitrate. You can also measure this value regularly at home. The individual values themselves are not important for this factor; it's only important that this ratio is maintained as closely as possible.

It's important to keep the PO₄³⁻ stable and make changes slowly and over several days or weeks. The nitrate value must always be higher than the PO₄³⁻ value, and the nitrate value is significantly less important than the PO₄³⁻ value. Therefore, the tendency towards change must always be regulated downwards. However, you should ensure that this does not lead to a limitation.

Wissensdatenbank - Fauna Marin

www.faunamarin.de

I think the figures are accurate. I have collected some of these data for my own lectures. Likely I have the cited article somewhere, but I just wanted to check quickly. The ratios scientific articles give for N and P are shown in the slides from one of my lectures.

How important is this ratio of 1:100 or 1:50? I myself and other reefers are successfull far outside of these ratios.

Like I said, science clearly says it has nothing to do with nitrate as a nutrient, because at these ratios the concentrations of nitrate with reasonable phosphate concentrations exceed the saturation concentrations for this nutrient, nitrate.

I’d like to see one of your lectures!

Do you think higher dissolved inorganic nitrogen and phosphorus compounds in our tanks are needed help to compensate for the relatively lower particulate/prey sources?

 

[Stamboli]

Imo, that isn’t sensible in the least.

It means that 1,000 ppm phosphate and 100,000 ppm nitrate is a good set of values.

I was also surprised reading this. But is there any proof what is definitely too much? I had success with 1.0 ppm phosphate and 100 ppm nitrate, and other reefers even with higher values. So hard to say what's too much.

 

[Troylee]

I was also surprised reading this. But is there any proof what is definitely too much? I had success with 1.0 ppm phosphate and 100 ppm nitrate, and other reefers even with higher values. So hard to say what's too much.

I’d say my tank looks pretty amazing! It’s sitting here… phosphate is super high!