Running ULNS vs keeping nutrients more than just detectable.

[ZapataInc]

Testing low nutrients doesn’t mean there are low nutrients in the system... rather, It means there is a low amount of accumulated nutrients dispersed in the water.

Many of y’all probably have experience with mass balances in one form or another. But for those that haven’t:

accumulation = Input – output + Generation -Destruction

In this simplification, we are looking at the water, then coral food and fish waste are our inputs, and corals and algae taking in the nutrients are our output. To keep things simple, we can ignore generation and destruction for now. To interpret this, if accumulation is low, it does not mean that our inputs are low. All it tells us is that our outputs are matching our inputs. This is called being at “steady state”. If there is an imbalance, then accumulation will increase. Most systems will adapt to a steady state environment, which is likely why natural reefs, with their great biodiversity, are quick to get back to 0 accumulation of nutrients.

Maintaining a low accumulation that is within a safe range is not bad (in my opinion). Conversely, having zero accumulation does not mean that your corals are receiving less food (I.e. You can have equal output in either scenario). However, at steady state, you could potentially be creating a limiting nutrient and thereby not maximizing growth. This is not necessarily a bad thing though either, and does not mean that growth is being restricted/capped. It is a fair analogy to think of this as ’possibly regulated growth‘. However, growth/color/etc could potentially still be maximized... It just notes that both options become a possibility in this case.

I run a ULNS.

• Nitrates test undetectable (<0.25ppm)
• Phosphates are usually around 10-20 ppb lately
• I don’t feed coral hardly ever. Maybe once or twice a month, if I feel like it.
• Not a heavy bio load (some damsels, a goby, a basslet, and 1 young Tomini tang in a 120g display)
• Fish feeding is maybe 5-6 days a week, once per day, in the morning, frozen food mostly, occasionally pellets
• No major algae issues. I had some turf algae that was starting to grow. Given that nothing really likes turf algae, Vibrant recently came to the rescue to wipe it out before it got bad.
• Corals look great! Amazing color all around. Softies, LPS, SPS including 1-2 dozen designer Acros and multiple anemones. Everything also has good polyp extension, and good growth.

Hope this data helps! Great thread

I might have to try Vibrant because I have some turf algae growing on my rocks.

 

[Adam]

Maintaining a low accumulation that is within a safe range is not bad (in my opinion). Conversely, having zero accumulation does not mean that your corals are receiving less food (I.e. You can have equal output in either scenario). However, at steady state, you could potentially be creating a limiting nutrient and thereby not maximizing growth. This is not necessarily a bad thing though either, and does not mean that growth is being restricted/capped. It is a fair analogy to think of this as ’possibly regulated growth‘. However, growth/color/etc could potentially still be maximized... It just notes that both options become a possibility in this case.

Removing coral growth from the equation. Do you think it's possible, with a very efficient export system, that there can be a very limited nutrient situation created in some systems? Even if the export system isn't the most efficient but it is removing a greater amount than is being introduced by the aquarist.

 

[CJD18]

Ill bring the wings if you supply the T-Bone steaks.

I got cold beer!

 

[CJD18]

This is an awesome topic.

My nitrates stay pretty low , my phosphate on the other hand is always high ..like .2ppm. all other parameters are Normal.

I feed fish only a couple times a week . (2max)Usually live brine shrimp or a third of a cube of frozen mixed reef food. I spot feed corals once a week . Usually some reef roids with a few drops of coral amino . Nothing major and small amounts . Occasionally I'll give some if the lps a pellet if I think of it . ( Acans ,candy canes,Duncan's ) I also have a constant minor algae problem ..that I've just grown to accept. This is in a 29 gallon set up with 5 small fish and approximately 50 pieces of coral .

From what I have read nutrients and available nutrients are very different . Just cause you have high phosphates doesn't mean they are actually available to the corals as food ,same with nitrates really . This applies to the ocean as well . There's always available nutrients for corals , although it may be super low levels it's mostly a usable form ..at least that's what I have gathered. Kinda like having a freezer full of frozen turkey ,you have lots but it's useless until it's defrosted and cooked .

In the new tank I'm going to take a different approach and run more carbon,gfo,bigger skimmer bigger fuge and more mechanical filtration. I'm going to attempt to basically bottom out the nutrients and add back what I need to keep levels acceptable vs always fighting to lower them ... always easier to add then remove .

Just my take on things View attachment 19122

Reef roids will raise your phosphates, they do mine, I cut way back on it.

 

[ActiveAngel]

Removing coral growth from the equation. Do you think it's possible, with a very efficient export system, that there can be a very limited nutrient situation created in some systems? Even if the export system isn't the most efficient but it is removing a greater amount than is being introduced by the aquarist.

Absolutely, that is a possibility. Nutrient export in that case would refer to algal growth, as nutrients would not be captured by filter socks or skimmers. So if you had enough algae growing, it could make a low nutrient system on its own. This is why many advocates of ULNS suggest a large refugium.

Another possibility that is non-coral that would take in nutrients is filter feeders like sponges and clams. But I assume we are grouping those with corals.

 

[Adam]

Absolutely, that is a possibility. Nutrient export in that case would refer to algal growth, as nutrients would not be captured by filter socks or skimmers. So if you had enough algae growing, it could make a low nutrient system on its own. This is why many advocates of ULNS suggest a large refugium.

Another possibility that is non-coral that would take in nutrients is filter feeders like sponges and clams. But I assume we are grouping those with corals.

I think that the people seeing colors get muted and stunted growth are either exporting too much or feeding too little. This will come into play more as systems mature and the coral mass increases. Then you have a situation where the export system and the coral are competing for available nutrients and the export is winning.

@jcook54 for instance was seeing this play out when he had a couple small fish in his frag tank and a macro growing on some of the rock in there. He doesn't have an extensive export system in place but the tank wasn't being fed much and the macro was growing well. His test results were showing zero for NO3 & PO4. After adding another fish or two and dosing Sodium Nitrate the coral colored back up. This type of complaint and solution is becoming more common. I would think there has to a balance where these nutrients are at least detectable for the coral to thrive. Otherwise why is the coral responding to NO3 dosing?

 

[ActiveAngel]

While nutrients are an important variable, the environment is equally if not more important. I don’t think I can make the same generalized statement for people seeing stunted corals or colors. I’ve seen both these occurrences happen is extremely heavily fed tanks, but each was due to different environmental factors.

 

[Eric_n_Ga]

Removing coral growth from the equation. Do you think it's possible, with a very efficient export system, that there can be a very limited nutrient situation created in some systems? Even if the export system isn't the most efficient but it is removing a greater amount than is being introduced by the aquarist.

BRS did some testing with a fuge and cubes of mysis. Bigger better lights =more photosynthesis =more nutrient uptake . They were testing 0,0 on both . With no bio load besides the cheato over weeks and that's a lot of food . So really by adjusting the photo period you could "tune" the fuge to get the export your looking for. This is actually the model I am going with for the new system . In a perfect world you could either over power the fuge and get near zero nutrients then dial it back to maintain the levels your looking for . Or dose to raise levels . I think you could keep pretty stable levels this way .

 

[ichthyoid]

Testing low nutrients doesn’t mean there are low nutrients in the system... rather, It means there is a low amount of accumulated nutrients dispersed in the water.

Many of y’all probably have experience with mass balances in one form or another. But for those that haven’t:

accumulation = Input – output + Generation -Destruction

In this simplification, we are looking at the water, then coral food and fish waste are our inputs, and corals and algae taking in the nutrients are our output. To keep things simple, we can ignore generation and destruction for now. To interpret this, if accumulation is low, it does not mean that our inputs are low. All it tells us is that our outputs are matching our inputs. This is called being at “steady state”. If there is an imbalance, then accumulation will increase. Most systems will adapt to a steady state environment, which is likely why natural reefs, with their great biodiversity, are quick to get back to 0 accumulation of nutrients.

Maintaining a low accumulation that is within a safe range is not bad (in my opinion). Conversely, having zero accumulation does not mean that your corals are receiving less food (I.e. You can have equal output in either scenario). However, at steady state, you could potentially be creating a limiting nutrient and thereby not maximizing growth. This is not necessarily a bad thing though either, and does not mean that growth is being restricted/capped. It is a fair analogy to think of this as ’possibly regulated growth‘. However, growth/color/etc could potentially still be maximized... It just notes that both options become a possibility in this case.

I run a ULNS.

• Nitrates test undetectable (<0.25ppm)
• Phosphates are usually around 10-20 ppb lately
• I don’t feed coral hardly ever. Maybe once or twice a month, if I feel like it.
• Not a heavy bio load (some damsels, a goby, a basslet, and 1 young Tomini tang in a 120g display)
• Fish feeding is maybe 5-6 days a week, once per day, in the morning, frozen food mostly, occasionally pellets
• No major algae issues. I had some turf algae that was starting to grow. Given that nothing really likes turf algae, Vibrant recently came to the rescue to wipe it out before it got bad.
• Corals look great! Amazing color all around. Softies, LPS, SPS including 1-2 dozen designer Acros and multiple anemones. Everything also has good polyp extension, and good growth.

Hope this data helps! Great thread

The first principle was stated above, though not in the same terms.
As mentioned, it also matters that nutrients dispersed in the water column are in a form we can measure (meaning inorganic salts, for our hobbyist test kits). Dispersed organic forms exist also, but generally do not show up when we test.

The rest, I take it, is a reference to Liebeg's law of the minimum?

"It states that growth is dictated not by total resources available, but by the scarcest resource (limiting factor)."

Liebig's law of the minimum - Wikipedia

en.wikipedia.org

 

[ActiveAngel]

The rest, I take it, is a reference to Liebeg's law of the minimum?

"It states that growth is dictated not by total resources available, but by the scarcest resource (limiting factor)."

Liebig's law of the minimum - Wikipedia

en.wikipedia.org

Not exactly, as I hadn’t looked into Liebeg’s Law before specifically. Usually, depending on the context, we more often hear them referred to as Monod Kinetics or Michaelis-Menten. But yes. We follow these fundamentals in our research.

 

[ichthyoid]

If we take systemic mass balance reasoning at face value, we might be tempted to conclude that the corals reach a steady state, settle in and that's it..
While the systemic kinetics are valid, the biology indicates that there is more going on 'under the hood' so to speak and may have been overlooked.
Many of us, including formal researchers, have encountered situations where an aquarium system in steady state seemed to be fine. Then corals specifically began to change. Often suddenly, for the worse & often without logical explanation.

That bacteria exist in formal relationships with corals and to their mutual benefit, is established-

Beneficial Microorganisms for Corals (BMC): Proposed Mechanisms for Coral Health and Resilience - PMC

The symbiotic association between the coral animal and its endosymbiotic dinoflagellate partner Symbiodinium is central to the success of corals. However, an array of other microorganisms associated with coral (i.e., Bacteria, Archaea, Fungi, and ...

www.ncbi.nlm.nih.gov

 

[ichthyoid]

Most of us have historically assumed that we provided sufficient nutrients & trace elements via water changes, dosing, air exchange & feeding. We usually pay little attention to the balance of such inputs, nor do we have convenient ways to quantify most of them.
Remembering that our aquariums are closed systems, it is conceivable that we unintentionally cause shifts in the balance of trace elements, via the above.
Example, of one such scenario: as corals and other organisms grow, some inevitably grow faster than others. Such changes naturally causes shifts in nutrient & elemental balance among species.

New research has shown that such shifts result in changes in the activity and diversity of bacteria. The above paper also illustrates that allelopathic as well as nutritional factors are involved. Allelopathic interaction in marine ecosystems is a powerful yet poorly understood phenomenon.
Some studies have shown that even pathogenic bacteria begin to dominate, in certain scenarios.

(PDF) Specific Effect of Trace Metals on Marine Heterotrophic Microbial Activity and Diversity: Key Role of Iron and Zinc and Hydrocarbon-Degrading Bacteria

PDF | Marine microbes are an important control on the biogeochemical cycling of trace metals, but simultaneously, these metals can control the growth of... | Find, read and cite all the research you need on ResearchGate

www.researchgate.net

 

[ActiveAngel]

Most of us have historically assumed that we provided sufficient nutrients & trace elements via water changes, dosing, air exchange & feeding. We usually pay little attention to the balance of such inputs, nor do we have convenient ways to quantify most of them.
Remembering that our aquariums are closed systems, it is conceivable that we unintentionally cause shifts in the balance of trace elements, via the above.
Example, of one such scenario: as corals and other organisms grow, some inevitably grow faster than others. Such changes naturally causes shifts in nutrient & elemental balance among species.

New research has shown that such shifts result in changes in the activity and diversity of bacteria. The above paper also illustrates that allelopathic as well as nutritional factors are involved. Allelopathic interaction in marine ecosystems is a powerful yet poorly understood phenomenon.
Some studies have shown that even pathogenic bacteria begin to dominate, in certain scenarios.

(PDF) Specific Effect of Trace Metals on Marine Heterotrophic Microbial Activity and Diversity: Key Role of Iron and Zinc and Hydrocarbon-Degrading Bacteria

PDF | Marine microbes are an important control on the biogeochemical cycling of trace metals, but simultaneously, these metals can control the growth of... | Find, read and cite all the research you need on ResearchGate

www.researchgate.net

Exactly. (But this may be digressing from the topic a little, and getting deep may also risk alienating readers). Our systems are constantly changing, and each change is incremental.

Keeping it practical for reefers, and on the topic of managing macro-nutrients in the water column, it’s good to likewise make similar incremental changes to your reef over time. And is why I don’t support making multiple dramatic changes simultaneously with the expectation that it will achieve a healthy steady-state aquarium quickly.

 

[ichthyoid]

Summary from the above paper states-
"The trace metals causing the strongest shifts to heterotrophic prokaryotic genera were Cu, Mn, Zn, Fe, and the Mix treatment, suggesting
those as key trace metals affecting heterotrophic prokaryotic community composition. The most susceptible genera to trace metals were hydrocarbon-degrading bacteria in the deep-water experiments, and uncultured bacteria in the surface water experiments. Interestingly, the most beneficiated and presumably best competitor taxa in all the experiments were hydrocarbon- degrading bacteria (particularly in surface waters where the strongest metal limitations are expected), revealing a potential predominant role of these type of bacteria in the cycling of metals and its associated cycling of organic matter in the ocean."

Which brings us to the core of the reason many have turned to ICP testing for our aquariums. It is logical to conclude that if we recognize the need for and truly want stability for our reefs and corals in particular, we need to recognize several things-
1-accurate measurements of the available trace levels is important (if not essential), in order to maintain their balance
2-addressing the needs of the organisms at the base of the food chain, bacteria in particular, is important for long term success.
3-there appear to be preferred clades of bacteria for specific corals, depending on the resulting state of condition desired (ie- color, heat tolerance, competitive/allelopathic properties, etc.)

About ICP Analysis for Saltwater Aquariums

So, why should you do ICP-Mass Spec analysis? What will it do for you and your corals? How it Works ICP-Mass Spec is not the most commonly used method in the aquarium world. The instrument we use is usually used to do testing to comply with the EPA regulations in environmental issues, so its...

www.icp-analysis.com

 

[ichthyoid]

Exactly. (But this may be digressing from the topic a little, and getting deep may also risk alienating readers). Our systems are constantly changing, and each change is incremental.

Keeping it practical for reefers, and on the topic of managing macro-nutrients in the water column, it’s good to likewise make similar incremental changes to your reef over time. And is why I don’t support making multiple dramatic changes simultaneously with the expectation that it will achieve a healthy steady-state aquarium quickly.

It speaks to the very heart of the issue, imho.
My premise: If we are focusing on growing the right bacteria, the coral will do great!
Kind of like the idea behind organic farming, but on a more formalized level.

 

[wantsummora acropora]

I will read those articles when I get home tonight. Thank you for posting them!

Do you think that as we get better and better at nutrient export that some aquarists have stripped their system of usable NO3 and the coral suffers as a result?
If someone has a very good export system in place with a long light schedule on it and decent sized coral mass that has a normal light schedule as well, but they're light feeders. I can see where this system will get deficient in NO3. Without a modification to feeding or reducing the effectiveness of their export the coral would then suffer. This then leads to nutrient dosing and things start getting better.

I'm trying to see what the correct correlation is between export and leaving enough soluble NO3 with out having to dose it. We all agree stability is key with reef aquariums. Just because the Alk, Cal and Mag are stable doesn't mean it's good if that stability is at too low of levels, say Alk 5.0; Cal 300; Mag 1100. Wouldn't the same hold true for NO3 and to a lesser extent PO4? Or am I over thinking it?

This is me 100%. I’ve run an ULNS for five years starting as a newbie. Some things did ok but many things did not. My big change was when I stopped running my skimmer 24/7 vs 6hrs a day, I removed the filter sock from the backup and I started dosing bacteria. No changes to feeding schedule. I’ve recently added the filter sock back just to keep my sump clean. My phosphates are at .19 due to a food dump by my auto feeder but they hover at around .06. My nitrates are at 8.6 and I try to keep them at around 8. I don’t shoot for a specific number but a narrow range. at one point, I was still dosing both nitrates and phosphates. Now it’s just nitrates at 12ml a day. I like running an ULNS because I think it’s easier to manage as I travel a lot but running a ULNS pretty much means just about everything is going to be “low” and your system can become “anemic” (the only way I can describe it).
Reef keeping could easily be a 2 year college course.

I'd like to have a discussion on just nutrients. Everything below is under the assumption that all other parameters are stable and in the proper range and that you have suitable lighting.

I have read a good bit on the nutrient requirements of coral over the last couple years. Without getting too technical and long winded... I know on most every coral reef across the globe, the nutrient level in the ocean water column is near nonexistent. I've also seen it mentioned in studies that these samples are usually taken in a specific time of the year, under the most ideal conditions. There is hope they can get more samples taken at different times of the year, like the rainy season, to compare values. At the moment, there is not a lot of information regarding runoff at reefs near smaller land masses. What is somewhat known is that there are times when more nutrient rich water is driven up from the ocean depths. This can happen during major storms or at times when there are large scale changes in the ocean currents. The wide time frames between occurrences should also make them an exception and not the rule as far as we're concerned (That is unless you stir things up the way I describe below). We all know that there are lots differences to wild coral reefs in open oceans vs our minute tanks. But one big difference is that on the reefs there are frequent phyto & zooplankton blooms that happen at night. These wild corals get most of their organic nutrient requirements from feeding on these nighttime blooms that our tanks don't naturally have.

I believe that in a ULNS system, sometimes the nutrients are taken up faster by the export method the aquarist has implemented, and the coral do not get enough, fish or no fish. Otherwise why are some people seeing muted color with poor growth and others are thriving? There must be some other common denominator between those having issues with a ULNS and those that aren't. In my mind that has to be feeding, nothing vs direct or broadcast coral feeding. I have seen the results of people that have had zero nutrients in the water and struggle with color and growth. But I don't know if or how much they feed their coral specifically. The common thing said to these people is feed more, add more fish or dose. But I seldom see it asked if they feed the coral. If these people do start dosing NO3 and possibly some PO4 the corals bounce back pretty quick and color up.

I initially thought that I didn't care about nutrient levels as long as they didn't get too high and there were no issues, like GHA, Diatoms or other nuisance algae. I have never been a big coral feeder. I did use some of the FeedMeAlgae products for a time, but I was never very consistent. At the same time my nutrients were seldom ever at or near zero and it's not something I'd ever striven for. Other than dosing amino's, coral feeding for me has been creating a detritus storm a couple times a week after lights out or what the coral gets from uneaten fish food. The more I think about it the more I think keeping higher nutrient levels puts us much closer to the tipping point where something bad happens. Why not keep things lower and keep the coral happy and colored up at the same time? This gives us more time to react if things start to climb.

I'd like to hear from everyone, whether you run ULNS or not.

What are your NO3 & PO4 levels?

What do you primarily feed the fish, Pellet or Frozen?

Do you regularly feed your corals?

If so, how often and what time of the day?

What products do you use to feed coral?

Are you happy with the coral appearance?

Do you have reoccurring algae issues?

my NO3 hovers around 8, PO4 .06 to .11
I feed Hikari meat pellets and Hikari algae pellets (that’s not the real name but what they are) 3 x per day 9Am 2:30PM and 6:30PM
I feed mysis shrimp soaked in Selcon or Brightwell amino’s to some corals, Phytogreens-s, Zooplanktos-s and Phytogold-s (broadcast) and I dose Manganese for my goni’s. I’m happy with the colors presented but as a caviars I don’t think Kessil A360x color is even close to Ecotech saturation but they do a good job.
I have no algae issues at all but that is only recently. I’ve battled algae constantly for several years.
I also daily dose bacteria.