Good Nitrate to Phosphate ratio for a reef tank?

[ScottR]

That is true. Corals in nature obtain a lot more nutrients from feeding than in the typical reef aquarium, so having very low P and N is typically not an issue out in the wild.

We can never mimic the ocean in our tanks. We basically do all we can to keep everything alive, beautiful and growing.

 

[Atu]

The Redfield ratio, which is 106:16:1 (C:N), is not a recommended value for growth, nor it’s the value in the ocean, nor nothing like that.
The Redfield ratio is simply the ratio at which said elements constitute part of the marine phytoplankton. This means, if you were to take a sample of phytoplankton and burn it you would expect to find those elements at that ratio. This doesn’t means they use it nor consume it at that ratio.
Our tanks consumes a lot more nitrogen that is expressed in that ratio by considering the denitrifying bacteria alone for example.

Beware of correlating your current parameters with what you are observing. Stable and full of coral tanks stop growing algae. I believe that if you were to go back to your previous parameters you would observe the same amount of algae in your tank as of right now.
Correlation does not implies causation.

 

[Eagle_Steve]

The Redfield ratio, which is 106:16:1 (C:N), is not a recommended value for growth, nor it’s the value in the ocean, nor nothing like that.
The Redfield ratio is simply the ratio at which said elements constitute part of the marine phytoplankton. This means, if you were to take a sample of phytoplankton and burn it you would expect to find those elements at that ratio. This doesn’t means they use it nor consume it at that ratio.
Our tanks consumes a lot more nitrogen that is expressed in that ratio by considering the denitrifying bacteria alone for example.

Beware of correlating your current parameters with what you are observing. Stable and full of coral tanks stop growing algae. I believe that if you were to go back to your previous parameters you would observe the same amount of algae in your tank as of right now.
Correlation does not implies causation.

With my tanks I have to respectfully disagree on going back and it being the same. They have been up for years, ran the same for those years and algae was always an annoyance. The only thing that has changed was where my N and P were. Yes fish grew and yes corals grew before. Now, my algae is just a little, which I want, but the corals are doing much better, the corals are growing faster, the algae is still able to be grazed by the fish and not be out of control. So yes, for me at least, these changes worked. Again, my tanks are my only reference and to me, that is all I need.

As for the ratio and all that, I have not researched it enough to know that much about it and never referenced it in relation to my tanks. I just know what works for my tanks.

That does not go without saying, stability and biodiversity is key. Even algae is good. I have seen tanks that are ULNS, and they look great. I have seen tanks thrive with 1.5 p and 50 n, and look awesome as well. I have also seen the opposite for people with low or high N and P.

The kicker is variables and how all tanks react differently. We all have different bacteria, different rock, different corals, where those corals are placed, flow varies, dead spots vary, and so on. The key is finding what your own tank(s) thrive under. I want a little algae but not a GHA farm. What I am doing achieves this for my tanks.

In the end we all want nice and healthy tanks and I think a ratio of some kind can be found for a tank. Whether that ratio works on another tank, one cannot say. But if my ratio does work, we shall call it the “Eagle Ratio”. Lol.

 

[ScottR]

With my tanks I have to respectfully disagree on going back and it being the same. They have been up for years, ran the same for those years and algae was always an annoyance. The only thing that has changed was where my N and P were. Yes fish grew and yes corals grew before. Now, my algae is just a little, which I want, but the corals are doing much better, the corals are growing faster, the algae is still able to be grazed by the fish and not be out of control. So yes, for me at least, these changes worked. Again, my tanks are my only reference and to me, that is all I need.

As for the ratio and all that, I have not researched it enough to know that much about it and never referenced it in relation to my tanks. I just know what works for my tanks.

That does not go without saying, stability and biodiversity is key. Even algae is good. I have seen tanks that are ULNS, and they look great. I have seen tanks thrive with 1.5 p and 50 n, and look awesome as well. I have also seen the opposite for people with low or high N and P.

The kicker is variables and how all tanks react differently. We all have different bacteria, different rock, different corals, where those corals are placed, flow varies, dead spots vary, and so on. The key is finding what your own tank(s) thrive under. I want a little algae but not a GHA farm. What I am doing achieves this for my tanks.

In the end we all want nice and healthy tanks and I think a ratio of some kind can be found for a tank. Whether that ratio works on another tank, one cannot say. But if my ratio does work, we shall call it the “Eagle Ratio”. Lol.

https://www.reef2reef.com/threads/1...mmonia-is-causing-your-algae-problems.558661/

This thread is worth a read.

 

[Eagle_Steve]

https://www.reef2reef.com/threads/1...mmonia-is-causing-your-algae-problems.558661/

This thread is worth a read.

It is a good read and have read it. What is funny is that I test ammonia every time I test. I know it may be a waste, but I have always done it lol. For me, I feel ammonia was not the issue, lack of diversity was. With nutrients so low, other things could not compete with the algae. I do understand that ammonia is produced no matter what and a lot can be consumed before I can test it. But with the tank being ULNS and heavily stocked, there was not much diversity. Bringing N and P up, I feel, helped with that diversity. When N and P were undetectable on any test kit used, things just were not right for my tanks. So I brought them up just to see what would happen. Took a while, as I am not gonna jump from undetectable to 10 in a day lol, but as it slowly went up, things got better. Algae did not grow as fast, corals looked better, pod population exploded, etc. I feel that the diversity this new environment created is what worked for my tank.

 

[ScottR]

It is a good read and have read it. What is funny is that I test ammonia every time I test. I know it may be a waste, but I have always done it lol. For me, I feel ammonia was not the issue, lack of diversity was. With nutrients so low, other things could not compete with the algae. I do understand that ammonia is produced no matter what and a lot can be consumed before I can test it. But with the tank being ULNS and heavily stocked, there was not much diversity. Bringing N and P up, I feel, helped with that diversity. When N and P were undetectable on any test kit used, things just were not right for my tanks. So I brought them up just to see what would happen. Took a while, as I am not gonna jump from undetectable to 10 in a day lol, but as it slowly went up, things got better. Algae did not grow as fast, corals looked better, pod population exploded, etc. I feel that the diversity this new environment created is what worked for my tank.

Everyone’s tank is different. And ask for an opinion and you’ll get a million. Everyone will tell you what products they use, methods of control, nutrients, parameters, lighting, etc. but it’s your tank. Only you know how it works. Only advice I can give is when changing something, do it gradually as to not shock the tank. In my SW tanks, I’ve never really battled algae or bacteria (thankfully). But in my freshwater tanks, it’s a different story.

 

[Reefahholic]

That is true. Corals in nature obtain a lot more nutrients from feeding than in the typical reef aquarium, so having very low P and N is typically not an issue out in the wild.

Exactly.

 

[Reefahholic]

Just thought I’d share this: I took a sample of water from the ocean. A bit offshore. I tested using Salifert kits. PO4 was almost immeasurable as was NO3. But we are not running a ocean in our tanks.

I took a Phosphate measurement in Galveston Texas a while back.

 

[Reefahholic]

Hard to understand how adding increasing nutrient levels or maintaining a certain nutrient ratio prevents nuisances algae growth. The notion is definitely popular, but there are simply too many uncontrolled variables and less than objective observations by proponents for me to have any confidence in these ideas.

As an experiment try running a reef with NO3 & PO4 at zero during the first year. You’ll never do it again after you see witness the issues it causes.

Then raise your PO4 to say 0.05 and your NO3 to about 10. You’ll quickly understand exactly what I’m talking about.

 

[Reefahholic]

im running my po4 at 0.06 and nitrates at 6ppm and everything is looking good. still raising my nitrate little by little to I get to the 10 mark. I also dose loudewolf nitrate and it works great

Yes indeed...sounds like you’re on track my friend!

 

[Sallstrom]

Hello!

Over the years this has been one of my favorite subjects. A while back I noticed my tanks doing a lot better with more NO3 than PO4.

When the NO3 matched the PO4 on the lower side the tank begin to grow hair algae in the sump, and dark brown algae on the rocks, overflow box, sand-bed and glass.

First let’s look at those low numbers. PO4 was down to 0.02-0.03ppm and NO3 was 1ppm.

As I bumped the the NO3 up to 3ppm...the algae begin to decrease. It continued to decrease even more as I slowly bumped it to 6ppm. Right now I’m holding it at 10ppm and the tank looks great.

I also increased the PO4 to 0.07ppm. This really got me thinking about the Red Field Ratio. Off the top of my head I think I heard you’re supposed to have 16 NO3 per 1 PO4.? Not sure how accurate that is, but would love to hear some thoughts on this subject as it may help us all.

Happy Reefing!

I'm glad you got good results in your tank.

I think the most important thing is to keep the nutrients from getting too low. Both Cyanobacteria and Dinoflagellates can do very well in low nutrients, and that's something we don't want. Maybe you had some of those?
I do not believe that a ratio is very important. As long as N and P are within the accepted range, I've seen happy corals and no unwanted algae.

 

[Reefahholic]

I'm glad you got good results in your tank.

I think the most important thing is to keep the nutrients from getting too low. Both Cyanobacteria and Dinoflagellates can do very well in low nutrients, and that's something we don't want. Maybe you had some of those?
I do not believe that a ratio is very important. As long as N and P are within the accepted range, I've seen happy corals and no unwanted algae.

Yes, I’ve had both Cyano and Dino’s with near zero levels of N & P. Once you start slowly dosing NO3 you’ll notice it gradually start to disappear.

 

[infinite0180]

My tank is in its first year, although my rock is a bit older from my first tank. When i began adding corals my NO3 was around 12 and PO4 was near zero. Everything was doing awesome, i was soo pleased. Then bam out of nowhere everything went downhill fast. Cyano and brown algae poping up and i lost some sps. Turns out my NO3 was down to around 4. So i slowly let my alk drop from around 9 to an 8 which helped and i began feeding more. Now i started dosing NO3. Im hoping to get it up to 8-10. We will see if it helps, i have a feeling it will...

 

[Atu]

With my tanks I have to respectfully disagree on going back and it being the same. They have been up for years, ran the same for those years and algae was always an annoyance. The only thing that has changed was where my N and P were. Yes fish grew and yes corals grew before. Now, my algae is just a little, which I want, but the corals are doing much better, the corals are growing faster, the algae is still able to be grazed by the fish and not be out of control. So yes, for me at least, these changes worked. Again, my tanks are my only reference and to me, that is all I need.

As for the ratio and all that, I have not researched it enough to know that much about it and never referenced it in relation to my tanks. I just know what works for my tanks.

That does not go without saying, stability and biodiversity is key. Even algae is good. I have seen tanks that are ULNS, and they look great. I have seen tanks thrive with 1.5 p and 50 n, and look awesome as well. I have also seen the opposite for people with low or high N and P.

The kicker is variables and how all tanks react differently. We all have different bacteria, different rock, different corals, where those corals are placed, flow varies, dead spots vary, and so on. The key is finding what your own tank(s) thrive under. I want a little algae but not a GHA farm. What I am doing achieves this for my tanks.

In the end we all want nice and healthy tanks and I think a ratio of some kind can be found for a tank. Whether that ratio works on another tank, one cannot say. But if my ratio does work, we shall call it the “Eagle Ratio”. Lol.

I love people disagreeing with me (within reason, lol) that’s how progress is made.

You said you had ultra low nutrients before, right? Might I ask what they were?

I’m gonna propose a different reasoning that might, or might not be, what had happened.
You didn’t had algae problems because of ultra low nutrients, you had ultra low nutrients because of algae problems. The algae were consuming all N and P as soon as it were available.
When you added more than it could consume your levels raised, in this scenario this allowed corals and other organisms to take hold and compete with the algae. Once the algae had competition it commenced to recede, and with help from grazers it ended up losing the battle.

Organism in our aquariums and in the sea release substances that inhibit or promote the growth of others. This allelopathic interactions play a big role that, being unable to measure them, we might attribute their effects to other things we do measure. Macroalgae in our refugiums might be inhibiting microalgae for instance, not starving it.
For instance, see this study.
“Allelopathic inhibition on red tide microalgae Skeletonema costatum by five macroalgal extracts”

They also release substances to bind nutrients, like iron forming complexes, possibly making it unavailable for other organisms.

What I’m trying to say is that a stablished population of algae would self promote and inhibit competition. The same goes for other organisms like corals.

 

[Dan_P]

As an experiment try running a reef with NO3 & PO4 at zero during the first year. You’ll never do it again after you see witness the issues it causes.

Then raise your PO4 to say 0.05 and your NO3 to about 10. You’ll quickly understand exactly what I’m talking about.

To recap, the factors of the hypothesis are the “first year” AND “low nutrient levels”. The obvious question is what about year two, three, etc.?

Even with this refinement of the nutrient hypothesis, the data that is available likely is dominated or biased by the experiences of new comers to the hobby whose aquaria are prone to all sorts of mishaps or experienced aquarists who witnessed the apparent correlation but not from those who don’t. Missing are the observations that do not follow the hypothesis.

You cannot use an entire reef aquarium with dozens of uncontrolled factors to prove the point. What can we discover with well controlled experiments in a test tube? I have a few spares to run experiments when we have some reasonable experiments to try.

 

[Brew12]

I love conversations about the Redfield Ratio. If I could maintain it in my system I absolutely would. It just isn't possible.

It is not a ratio of NO3 to PO4. It is a ratio of all forms of carbon to nitrogen to phosphorus. It doesn't matter if they are organic, non organic, gas or solid. We have no way to accurately measure it in our system. If we can't measure it, we can't maintain it.

As for the low nutrients in the ocean, that is deceptive. Every measurement we take is nothing more than a snapshot of current conditions. I view the ocean as a high nutrient system even if the measured readings are low. Fresh nutrients are continuously being brought into the reef. It's like a small candy dish that is continuously being refilled. Our tanks would be like a large plate of food. It tends to be higher at most times but if not replenished can completely run out.

 

[Reefahholic]

To recap, the factors of the hypothesis are the “first year” AND “low nutrient levels”. The obvious question is what about year two, three, etc.?

Even with this refinement of the nutrient hypothesis, the data that is available likely is dominated or biased by the experiences of new comers to the hobby whose aquaria are prone to all sorts of mishaps or experienced aquarists who witnessed the apparent correlation but not from those who don’t. Missing are the observations that do not follow the hypothesis.

You cannot use an entire reef aquarium with dozens of uncontrolled factors to prove the point. What can we discover with well controlled experiments in a test tube? I have a few spares to run experiments when we have some reasonable experiments to try.

I’ll always avoid running low nutrients in a reef no matter if it’s the 1st year or 4th year. When I say low, I’m referring to PO4 at like 0.01 and NO3 at 1. Or maybe a little higher. For me, it just doesn’t work and I have issue after issue. Yet as soon as I bring them up...the tank thrives.

There’s good reason why some of the masters in this hobby run a reef the same way. All the parameters and names are listed below in Mike’s thread if you’d like to take a look.

https://www.reef2reef.com/ams/tank-parameters-of-some-masters.263/


With that said...are some people with large acropora dominated systems or refugiums packed full of cheato getting zero numbers for N & P? Well of course they are. Massive colonies and large cheato beds are sucking those nutrients up. Are the numbers really zero. Of course not! You know this by looking at bright green thriving Marcos or large Acropora colonies.

 

[Reefahholic]

As for the low nutrients in the ocean, that is deceptive. Every measurement we take is nothing more than a snapshot of current conditions. I view the ocean as a high nutrient system even if the measured readings are low. Fresh nutrients are continuously being brought into the reef. It's like a small candy dish that is continuously being refilled.

Exactly!

 

[Randy Holmes-Farley]

I also increased the PO4 to 0.07ppm. This really got me thinking about the Red Field Ratio. Off the top of my head I think I heard you’re supposed to have 16 NO3 per 1 PO4.? Not sure how accurate that is, but would love to hear some thoughts on this subject as it may help us all.

My thought is a ratio is a really poor way to think of nutrients. How does a ratio make any sense? If nitrate is 1,000 ppm, does that mean an optimal phosphate level for that tank is 10 ppm? Same at very low levels. If nitrate is 0.00001 ppm, should phosphate optimally be 0.000001 ppm?

I cannot see any reason to not independently target them at desirable levels (whatever you believe those to be, rather than targeting a ratio.

 

[Reefahholic]

My thought is a ratio is a really poor way to think of nutrients. How does a ratio make any sense? If nitrate is 1,000 ppm, does that mean an optimal phosphate level for that tank is 10 ppm? Same at very low levels. If nitrate is 0.00001 ppm, should phosphate optimally be 0.000001 ppm?

I cannot see any reason to not independently target them at desirable levels (whatever you believe those to be, rather than targeting a ratio.

My thought is a ratio is a really poor way to think of nutrients. How does a ratio make any sense? If nitrate is 1,000 ppm, does that mean an optimal phosphate level for that tank is 10 ppm? Same at very low levels. If nitrate is 0.00001 ppm, should phosphate optimally be 0.000001 ppm?

I cannot see any reason to not independently target them at desirable levels (whatever you believe those to be, rather than targeting a ratio.

I agree. Doesn’t seem like a good ratio. 16 to 1 is too much for me. Not sure where that number comes from and maybe it’s a great number for the ocean, but not as good for my reef.

I like my PO4 about 0.05 - 0.15 & NO3 5-20.

I try not to chase numbers so if they’re in that range on the higher end I’m fine with it, but for better colors I tend to like lower. Like PO4 at 0.07-0.1 and NO3 at 5-15. Works well for me around in there.