My Collected Thoughts on N and P Dosing

[jda]

Since this is the SPS forum, has anybody seen any evidence that SPS feed on anything that is offered to them in captivity, or that they get any benefit from it? Lasse had some compelling research that aminos are used up by single cell organisms before they get to the corals (SPS are outcompeted, but they can absorb aminos through the skin tissue) and there appears to be no evidence that SPS can eat reef roids, chili, or the like. Most invert biologists will maintain that the polyps are mostly for gas exchange and catch food as a secondary purpose.

N and P are building blocks and not food. More of them is not like having more carbon/sugar that the corals will get from the zoox (or if they can catch food).

All of this being said, light is the only thing that "feeds" SPS that we know for sure. I agree that some people starve their corals, but it is light based and not N and P based, or based on offered/prepared foods.

 

[FlyPenFly]

Taken as a percentage of time, I would also say my mouth is mostly used for gas exchange, especially when I'm sleeping. However, it's also the primary way I eat food objects as well.

The only evidence I've seen of corals eating Reef Roids is that some of my corals throw up mucuous nets catching food particles that they seem to retract back. Most acros also start getting extreme PE when I turn off every pump and spot feed for ten minutes. If I do the exact same thing and don't feed anything, there is no reaction from the SPS. So yes, at least in my experience, reef roid particle sizes seem to trigger a feeding response in most of the SPS that I have.

They also seem to enjoy fish poop, when my tang takes a big dump, I do see some more PE.

 

[jda]

A feeding response is no proof that any nutritional value is gained. People think that messenterial filaments are a good thing since they see a piece of food attached to them every now and then, but they energy expended by the coral is enormous often to the detriment of the coral. Mucous is expensive and takes energy. That is why I am asking for real proof from an actual study or something resembling a study - everything that is out there says otherwise and that there is no benefit. We know FOR SURE that corals don't need food because there are too many exceptional reefs that don't feed their corals. I just wonder if people assume too much in the face of all of the facts that they are probably not doing anything at best, and maybe even hurting stuff at worst with energy spent and not as much energy getting returned. I guess that if people want to believe that they are feeding corals, then fine, but it probably is not true.

I don't care for the false equivalency of a human mouth (who also has a nose) to actual science done by real biologists like Dr. Ron and Fenner about coral feeding and respiration for a symbiotic coral that has all food that it could want delivered to it by dinoflagelites. The biologist that we talked with in the Coral Sea said that the distant acropora reefs were devoid of nearly all plankton, but the lagunal species closer to the shore could often get food - nems, LPS, softies as well as many NPS corals. He said that were there is plankton, there is s lot of NPS stuff.

 

[SeaDweller]

@TitanCi are you’re sps growing, good PE, thick healthy tissue, color etc. I only ask because I don’t think I’ve seen any close ups of your Sps.

Everything is doing great, thanks bud! I don’t have great pics cuz my iPhone and filter don’t do that great of a job. Let me take some pics anyway, I have 120 frags and some colonies I need to track any way.

 

[FlyPenFly]

The human mouth thing is just a joke, take it easy.

The energy expended by the coral to take up and absorb the food would seem to imply that it's worth it to them because you can absorb a hell lot of nutrients faster by eating.

I agree that a study would be best but lacking one, feeding seems to work ok for me. It would be nice to know if it does anything or hurts something.

Anecdotally, I've rescued some fuzzy polypie SPS that died off (ATO fail salinity spike in a nano) but regrew into it's old skeleton by feeding it every other day. It regrew remarkably fast like I couldn't believe. A large 3 branch frag gaining back half inches of big polyp tissue in a week.

Ultimately, I would imagine some acros are more friendly to feeding than other acros. Millis and other long polyp acros are probably evolved to be geared towards more food capture and smooth skin small polyp acros like Red Dragons are probably not as geared towards feeding.

 

[shred5]

Since this is the SPS forum, has anybody seen any evidence that SPS feed on anything that is offered to them in captivity, or that they get any benefit from it? Lasse had some compelling research that aminos are used up by single cell organisms before they get to the corals (SPS are outcompeted, but they can absorb aminos through the skin tissue) and there appears to be no evidence that SPS can eat reef roids, chili, or the like. Most invert biologists will maintain that the polyps are mostly for gas exchange and catch food as a secondary purpose.

N and P are building blocks and not food. More of them is not like having more carbon/sugar that the corals will get from the zoox (or if they can catch food).

All of this being said, light is the only thing that "feeds" SPS that we know for sure. I agree that some people starve their corals, but it is light based and not N and P based, or based on offered/prepared foods.

They can catch food I have seen it, I can not say all can catch larger particles we can see. I believe some eat bacteria.
How do we know our corals are not catching food or bacteria. Some of it may be to small for us to see.
I have seen some SPS take particles as large as cyclopeeze.
I can not say for sure they digest the food but I have seen them catch and take it in.
I have had this discussion a few times with Eric Borneman.

 

[hatfielj]

Since this is the SPS forum, has anybody seen any evidence that SPS feed on anything that is offered to them in captivity, or that they get any benefit from it? Lasse had some compelling research that aminos are used up by single cell organisms before they get to the corals (SPS are outcompeted, but they can absorb aminos through the skin tissue) and there appears to be no evidence that SPS can eat reef roids, chili, or the like. Most invert biologists will maintain that the polyps are mostly for gas exchange and catch food as a secondary purpose.

N and P are building blocks and not food. More of them is not like having more carbon/sugar that the corals will get from the zoox (or if they can catch food).

All of this being said, light is the only thing that "feeds" SPS that we know for sure. I agree that some people starve their corals, but it is light based and not N and P based, or based on offered/prepared foods.

This is an excellent question and one I have also wondered. I occasionally try to target feed my SPS reef roids and I have yet to see the polyps actually grab a particle and ingest it like you see with LPS and Anemones. I have seen them temporarily hold on to larger pieces of frozen food but they always release it in the flow. I have not been able to find any video footage showing sps actually ingesting these particles either.
I would love to hear what researchers know about this subject. It's clear that many of our most common SPS come from reefs where the water is very turbid at times and full of particulate matter that we are told they feed on frequently. But, I don't see there being any good research about this happening in reef aquariums or if we are even trying with the right food.

 

[hatfielj]

They can catch food I have seen it, I can not say all can catch larger particles we can see. I believe some eat bacteria.
How do we know our corals are not catching food or bacteria. Some of it may be to small for us to see.
I have seen some SPS take particles as large as cyclopeeze.
I can not say for sure they digest the food but I have seen them catch and take it in.
I have had this discussion a few times with Eric Borneman.

What did Borneman have to say about this subject?

 

[jda]

There are studies, and they all say that SPS don't get anything from food. Some people confuse "coral" studies, but LPS, softies and of course NPS are totally different animals than SPS but everybody has seen these eat. These studies are older and are referenced plenty on WWM if you want to venture over there. Not feeding SPS corals was an "old fact" of reefing before it became a big-money industry to sell supplements and coral food - we had far less SPS back then, but still the same species were around from deepwaters (with almost no polyps) to millepora (with a ton of polyps) and even some Spaths and Prostrata which are hairier than Millepora at times.

Again, it is more likely that the corals evolved to be hairy or smooth in response to gas exchange and not so much feeding - nobody is for sure, but there is evidence for this.

Of course, not needing to feed them (which is plain that they can thrive without direct feeding), is not proof that they might benefit if we did it right or had the right food.

For now, I just tell people to do the absolutely best that they can with light. I don't discourage people from feeding coral unless they are fighting algae or otherwise have too many N and P on the backend.

 

[dragon99]

Since this is the SPS forum, has anybody seen any evidence that SPS feed on anything that is offered to them in captivity, or that they get any benefit from it? Lasse had some compelling research that aminos are used up by single cell organisms before they get to the corals (SPS are outcompeted, but they can absorb aminos through the skin tissue) and there appears to be no evidence that SPS can eat reef roids, chili, or the like. Most invert biologists will maintain that the polyps are mostly for gas exchange and catch food as a secondary purpose.

There's plenty of research supporting the idea that corals capture food.
"Heterotrophy accounts for between 0 and 66% of the fixed carbon incorporated into coral skeletons and can meet from 15 to 35% of daily metabolic requirements in healthy corals and up to 100% in bleached corals. Apart from this carbon input, feeding is likely to be important to most scleractinian corals, since nitrogen, phosphorus, and other nutrients that cannot be supplied from photosynthesis by the coral’s symbiotic algae must come from zooplankton capture, particulate matter or dissolved compounds."
Houlbrèque F, Ferrier-Pagès C. Heterotrophy in tropical scleractinian corals. Biol Rev. 2009; 84(1): 1–7. https://onlinelibrary.wiley.com/doi/full/10.1111/j.1469-185X.2008.00058.x [PubMed] [Google Scholar]

Here's a study specifically looking at acropora species. Especially interesting since it's goal is to identify what foods are most beneficial.
https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0188568

Here's a study that specifically looked at the reef chili, reef roids, etc. Abstract suggests that some SPS can benefit from feeding these foods.
https://www.researchgate.net/public...ts_of_light_water_motion_and_artificial_foods

 

[Charlie’s Frags]

Some big names have been checking out this thread

 

[jda]

Is that SPS study the one that says that SPS might benefit from feeding, but they have no idea what to feed them? I don't have time to read it right now, but it seems familiar.

Again, I am kinda looking for some answers, not speculation. We are all pretty good at speculating on our own, right?

 

[watchguy123]

What about the interaction between light, nutrients (nitrates in particular) and alkalinity.

We measure nitrates but I’ve never measured ammonia nor ammonium—never considered it. Nitrates may or may not be the specific molecule that is critical but it’s used as a marker for “nutrient” levels.

Not sure what the best alkalinity level is but there seems to be a current trend to get closer and closer to saltwater levels (7 ish give or take). When I started reefing, alkalinity levels were suggested around 11-12 dKh but have moved into the lower range of alkalinity for some time. Interestingly, BRS just did a video on alk levels and found better growth with “high” levels of alkalinity.

Seems that when nitrates get zero-ish and if alkalinity is not in a lower range 7-8 dKH that acro tips burn. The anectodal experience is that if one maintains alkalinity at higher levels above approximately 8 and the tank start moving nitrates toward zero that the acro tips start burning and this is remedied by either dropping alkalinity level or increasing nitrates.

I find if I don’t supplement nitrates (kno3) that my nitrates will approach zero. I certainly feed heavy (fat fish) with a large number of fish but I have lots of nutrient export. So, I add nitrates to both keep nitrates from bottoming out and it also keeps phosphates low.

But your point is so correct. How many things do we do with our limited scientific knowledge that are not helpful, maybe benign or perhaps even harmful.

 

[FlyPenFly]

High alkalinity and elevated level seems to accelerate growth, not a big secret in coral farms or the BRStv test. I wonder if it also makes coral more efficient at nutrient uptake helping them outcompete algae and other organisms in nutrient absorption.

 

[jda]

Let's remember that burnt acro tips, in this case, are from the SPS growing so fast that the tissue cannot keep up. You have to keep alk down to limit the calcification... in the 6s. Ocean got this right...low alk and low N and P give the fastest growth.

 

[FlyPenFly]

High blue+ spectrum light, high random indirect flow, high levels (alk,Ca,mg, trace), high pH, and moderate amounts of nutrients grow SPS quicker with better coloration. I’m pretty sure this is going to prove out to be fact in the very near future. The tricky part IMO, at this point is the type of microbiome life and diversity that exist in mature tanks that promote success. I am curious if that’s something that can be accelerated as well instead of just developing over a few years in wel kept systems.

With just elevated levels some SPS grew at double the rates, at least for frags even in new systems.

 

[29bonsaireef]

With just elevated levels some SPS grew at double the rates, at least for frags even in new systems.

Just curious, double the rate compared to what? A lower level system?

What about compared to corals on a natural reef that grow a 1' or more a year, and receive warmer spectrums of light, lower alk, and lower N&P levels than most reef tanks?

 

[FlyPenFly]

Just curious, double the rate compared to what? A lower level system?

What about compared to corals on a natural reef that grow a 1' or more a year, and receive warmer spectrums of light, lower alk, and lower N&P levels than most reef tanks?

Typical level reef system. I recommend checking out the video yourself.

You would have to specify which reef and you’d have to have very similar frags with a somewhat larger sample size to draw any conclusions if the ocean grows faster than man made systems. It probably depends on species and other factors.

 

[spartanman22]

I am also of the opinion that dosing either is unnecessary. I've dosed both, but found that it can be tricky maintaining the proper levels unless you are dosing both at the same time. I also agree that you need a decent amount of Nitrate and Phosphate for acros. I keep mine around 5/0.05. I think the question is, how do you do that without dosing? If you're using some type of reduction device (Chaeto, ATS, Bio Pellets, GFO, etc.) it's easy, you just reduce and eventually eliminate if needed those devices.

So what if you don't have any type of reduction and your "nutrients" are still too low or undetectable? I see numerous people advise, "Feed More". IMO this is a little too vague. For instance, if you have one fish in your 100g tank and you dump a bunch more food in, I don't think it's going to help your corals. Rather than "Feed More", I subscribe to "Add More Fish...and Feed Them". IMO there is a balance of the right amount of fish for each tank and when you reach that balance, your Nitrates and Phosphates will maintain themselves. You just slowly add fish and feed those fish until you hit the level you want.

This is more or less the mantra I follow. 1.5 months ago my tank looked like this:

I then had to remove a bully flame back angel, fast growing baby rabbit, and a bully Wrasse. Couple that with 4 weeks of business travel and came back to some paled SPS and gha. NO3 and PO4 were non-detect. Have since added more fish but it takes time. There is a natural balance to all of this and sometimes dosing isn’t the best option.

 

[watchguy123]

Let's remember that burnt acro tips, in this case, are from the SPS growing so fast that the tissue cannot keep up. You have to keep alk down to limit the calcification... in the 6s. Ocean got this right...low alk and low N and P give the fastest growth.

I am not sure I am following this. I am not arguing the point just trying to understand the reasoning. Some points have been brought up which merit consideration

Why do you think burnt tips are from accelerated growth (I presume you mean calcification and in particular skeletal growth). Why do you presume calcification is accelerated and why do you presume tissue cannot keep up. Perhaps something else is taking place that is not increasing calcification but simply injuring the tissue.

Lastly, this is the part I am most confused about. You state: “You have to keep alk down to limit calcification...in the 6’s.” And then your next sentence seems to contradict this, “Ocean got this right...low alk and low N and P give the fastest growth”. Maybe I just am missing the point but it seems in one sentence low alk slows calcification and in the next sentence low alk and low N and P increases calcification.

The next responder, Flypenfly, states that “....high levels (alk, ca, mg and trace), high pH, and moderate amounts of nutrients grow SPS quicker and with better coloration.”

So which is it higher alk or lower alk, low nutrients or moderate amount of nutrients.