DiscusHeckel
Acropora Gardener
Ding Ding Ding
agree with this 100%.
Me too.
Guess the Phosphate level
- Thread starter Thales
- Start date
Me too.
Acronic
The Fifth Master
Now we are getting somewhere!
We may not be able to say exactly what level of inogranic nitrogen and phosphorous harm corals but we, at the very least, can try to understand why. A simple and seemingly obvious place to start is with OXYGEN!
Oxygen plays a huge role in the day to day processes on the reef and its something that doesn't get discussed very often (maybe because its boring
). We know that "elevated" levels of inorganic nitrogen and phosphorous lead to decreased oxygen on the reef. It wouldn't surprise me in the least to think that our reefs experience localized hypoxia. Perhaps only for short periods at a time. Excess decaying matter will suck up vast amounts of oxygen. Keeping detritus to minimal amounts will offset that. Perhaps alot of what we see are the corals re-allocating their energy to different processes based on its surrounding environment. For instance, when the lights go out the polyps feeding tentacles come out to feed. When the lights come on, the polyp tentacles retract and the coral resumes allocating energy to displace oxygen and organic compounds for calcification while receiving sugars from the zoox for photosynthesis. If radiation levels change or water turbidity changes, the coral may have to allocate more energy into the production of chromoproteins to protect its tissue from radiation damage or producing flavoproteins for the removal of radicals causing oxidative stress. Simply catching pray involves using energy for muscle contractions or fiering neurons, energy that was once being used by the coral for one thing is now re-allocated to another process. Offering the corals means to do one thing allows them to focus on another. If I target feed a coral, it doesn't have to work as hard to eat. If I increase oxygen saturation, the coral doesn't have to work as hard to breath. If I increase light, the coral doesn't have to work as hard to photosynthesize. If I decrease light, the coral doesn't have to work as hard to build protective pigments etcetera.
Any long term SPS keeper will tell you that the "BEST" colours never last forever. You may achieve them again but keeping them a constant is not gonna happen. My believe is that the reef is forever changing and its inhabitants must change and adapt with it or risk peril. "Survival of the fittest" rings so true in this hobby, it's the nature of things.
GroktheCube
New member
Trying to at least somewhat approximate nature (TONS of food in the water, fairly low dissolved inorganic nutrients) is likely a safe starting point.
The question is when/how inorganics hurt corals. They can obviously promote algae growth, which is unsightly and potentially harmful at times (smothering, allelopathy). Anecdotal observation suggets that elevated NO3/PO4 may be directly harmful to growth, health or color. Some controlled tests show PO4 impairing calcification, but others seem to show nothing or the opposite. It's been pretty well established in controlled tests that coral can utilize inorganic N.
There's a lot we don't know. As far as I know, a clear mechanism for toxicity hasn't been established. I know deposition of calcium phosphate is one proposed way P could be harmful, along with zooxanthellae overgrowth, but nothing solid.
The question is when/how inorganics hurt corals. They can obviously promote algae growth, which is unsightly and potentially harmful at times (smothering, allelopathy). Anecdotal observation suggets that elevated NO3/PO4 may be directly harmful to growth, health or color. Some controlled tests show PO4 impairing calcification, but others seem to show nothing or the opposite. It's been pretty well established in controlled tests that coral can utilize inorganic N.
There's a lot we don't know. As far as I know, a clear mechanism for toxicity hasn't been established. I know deposition of calcium phosphate is one proposed way P could be harmful, along with zooxanthellae overgrowth, but nothing solid.
OXYGEN!
This 3 part series by Eric Borneman may be of interest. I think it's an excellent read:
http://www.reefkeeping.com/issues/2005-06/eb/index.php
http://reefkeeping.com/issues/2005-07/eb/index.php
http://reefkeeping.com/issues/2005-07/eb/index.php
I don't think elevated levels of PO4 and NO3 lead to depleted oxygen levels. PO4 is alkalinity and NO3 is oxygen rich . NO3 will raise ORP. NO3 will deplete alk though but puts it back if the oxygen in it is used by denitrifying bacteria in anaerobic mode an the N forms N2 gas which escapes the tank. Ammonia and organic compounds do deplete O2 as bacteria degrade them and form the inorganic nitrogen and phosphate.
Heavy coral cover may offset oxygen depletion a lot during periods of photosynthesis and might even lead to hyperoxic conditions in some tanks but night time hypoxia might be more of an issue in a tank with enough organic degradation to produce eutrophic water.
This 3 part series by Eric Borneman may be of interest. I think it's an excellent read:
http://www.reefkeeping.com/issues/2005-06/eb/index.php
http://reefkeeping.com/issues/2005-07/eb/index.php
http://reefkeeping.com/issues/2005-07/eb/index.php
I don't think elevated levels of PO4 and NO3 lead to depleted oxygen levels. PO4 is alkalinity and NO3 is oxygen rich . NO3 will raise ORP. NO3 will deplete alk though but puts it back if the oxygen in it is used by denitrifying bacteria in anaerobic mode an the N forms N2 gas which escapes the tank. Ammonia and organic compounds do deplete O2 as bacteria degrade them and form the inorganic nitrogen and phosphate.
Heavy coral cover may offset oxygen depletion a lot during periods of photosynthesis and might even lead to hyperoxic conditions in some tanks but night time hypoxia might be more of an issue in a tank with enough organic degradation to produce eutrophic water.
Last edited:
Acronic
The Fifth Master
Nice, I dont believe I have read those articles yet, thanks.
I should have been more clear in saying that elevated inorganic N and P can "lead" to depleted oxygen levels on the reef (the actual reef
) but really only in areas were there is high human activity and agricultural goings' ons' leeching fertilizers into the oceans etc causing eutrophication. However, the principal is there. Also, with all the bacterial and antibiotic additives these days it's easy to see how one could artificially incubate eutrophic conditions. Side bar; I wonder if some of the trace elements offered these days that "control" zoox populations contain copper? Hormones aside.... oh geez, now Im rambling
Allmost
New member
Nice, I dont believe I have read those articles yet, thanks.
I should have been more clear in saying that elevated inorganic N and P can "lead" to depleted oxygen levels on the reef (the actual reef
Side bar; I wonder if some of the trace elements offered these days that "control" zoox populations contain copper? Hormones aside.... oh geez, now Im rambling
I think the idea that oxygen needs more attention by reef keepers is a good one for aquariums ,particularly localized nightime hypoxia near the base of corals or in areas where growth has limited the flow to the polyps. I'm glad you brought it up . I suspect some of the base stn that occurs in some tanks might relate to it at least as one factor ; but I don't know that.
The presence of high levels of PO4 and NO3 while they don't deplete O2 levels are products of the degradation of the organics which release them and /or the respiration or excretion of ammonia by some animals.
Most of the the bacteria involved in degrading non refractory organics and ammonia do use oxygen even in anaerobic activity when they get it from NO3 .
Organics including C N and P in various molecules are added to the aquarium primarily via food.Some come from stores produced via photosynthesis or feeding from coral and algal exudates and some from expelled excess by other animals including fish.
Some organics like fulvic and humic acids are refractoy and resist bacterial activity .Some may degrade in localized areas when conditions are right, perhaps in detritus accumulations or hypoxic areas for example.
My understanding of organics is limited despite rather extensive reading . We can't even test for them with hobby equipment ,so I think we tend to ignore them. There are likely hundreds of thousands of such compounds maybe more in the sea .They change in rsponse to externals like pH, presuure,and so on.Some are bioavailable; some are not .Thr is a long way to go in leaning here.
In a natural setting the organic C ,N and P including planktonic organisms as well inorganic P and dissolved nitrogen well up through the reef leaving small amounts of inorganic P and dissolved nitrogen at the surface, as they are consumed along the way and diluted.At least that's the standard version.
If organics isn't confusing the issue of optimal conditions for corals in a reef tank enough. Then we can get into which organisms thrive at what levels of nutrients and questions about nutrient balance and ratios.
In a natural setting the organic C ,N and P including planktonic organisms as well inorganic P and dissolved nitrogen well up through the reef leaving small amounts of inorganic P and dissolved nitrogen at the surface, as they are consumed along the way and diluted.At least that's the standard version. In this scenario the nutrient levels vary at different depths.
The surface waters are described as oligotrophic(scarce nutrients). They support oligotrophic organisms(those that thrive in low nutrients) including micro fuana and bacteria as well as corals Copiotrophic aka eutrophic waters(high in nutrients) support more copiotrophic organisms. It has been suggested that more pathenogenic bacteria are copiotrophic. Red turf algae and some others seem to be as well. We do have a study citing a very low PO4 level as a limiting factor for phytoplankton in one of Randy Farely's articles along with an overall recommend ratio for PO4 at ,0.02ppm IIRC as well as several older studies cited therein regarding the "inhibition" of calcification at high PO4 levels. Now we have a few new ones that show increased overall "growth" for certain sps but decreased density. I don't think that's much different, The calcification process is alterd in both cases. Is that a good thing or a bad thing;I'm not sure but it's altered. I don't know how anyone would know it's insignificant. I wonder how it happens. Is it simply the poisoning of calcium carbonate nucleation sites or is it tied to ATP and more energy to push more calcium to nucleation sites in the skeletal matrix than usual.Is this good for the coral? Does it inhibit the coral's ability to direct the optimal placement of the skeletal matrix?. I don't know but it's altered.
So, we are faced with a very compicated soup with a ton of intedependent variables which makes it hard to say much about any specific part of the mix beyond anecdotal observations , what knowledge we have about how corals use phosphate ,nitrogen and organics and the chemsitry of it all. The anecdotal observations are many and varied to some extent.
In tanks the reduction in nutrients doesn't happen with the same level of efficiency and dilution as it seems to do on a reef leading to elevated levels of PO4 and NO3. I wonder if organic compounds build up to unfavorble levels as well and what the effects on the microbiota and coral holibonts are in eurtrophic water.Personally, I think but do not know except for my aquariums that limited PO4( .02ppm to .04ppm as measured consitently and daily over 5 years time with a hanah 713 colorimeter ) and NO3 at barely detectable levels per the Salifert will provide enough phosphate and dissolved nitrogen to meet the needs of the corals and other animals I keep while limiting copiotrophic organisms like some algae. In my case these levels have provided a really good 5 year run in terms of coral color and health with minimal nusiance algae. Could that happen in more eutrophic water? Maybe. I don't think so in my tanks since whenever these levels go up a little. I see an uptick in nuisiance algae and a decline in the overall vibrancy of some corals like seriatopora and some montipora. I've also seen some paling if they go too low. Is that the same for every tank I doubt it but maybe ?
I got on a rambling and not much of this post relates to oxygen but I had fun anyway.
Thales
Active member
I should have been more clear in saying that elevated inorganic N and P can "lead" to depleted oxygen levels on the reef (the actual reef
Fantastic clarification. Thanks! I think this kind of accuracy is very important in discussions about what goes on inside our glass boxes. The hobby is complicated and we don't have a great handle on what is going on, only generalities that may or may not pan out in the future. Making the effort to be accurate in discussions removes a level of complexity. So again, thanks!
Thales
Active member
I think this would make for an excellent simple side by side test for a someone or a club to run. Like I said earlier, I think we need more basic tests to see where we should be looking.
Acronic
The Fifth Master
Agreed. The effort should also add a level of diplomacy. An argument is nothing but a triangle. Two points that must intersect, no matter how obtuse.
I think this would make for an excellent simple side by side test for a someone or a club to run. Like I said earlier, I think we need more basic tests to see where we should be looking.
I'm glad I am a cronic and not a someone or a club :hammer:
Acronic
The Fifth Master
Interesting theory
Im glad you mentioned humic acid. It sparked some interesting thought. Im wondering if corals trade glucose to microbes in the mucus membrane for minerals and whether these microbes could play a role in disease prevention. Also stirring some thought on how GFO could negatively affect sps.
I know right! but its fun
I want to write more but my laptop is dead and sleep is calling
Thales
Active member
CW from the OC
New member
Interesting read, thanks for writing and sharing it!
AugustWest
Premium Member
Very interesting. It's very easy to get caught up in number chasing. I got caught up in it a little myself when I picked up my Hanna ULR checker. Then I realized it's not as accurate as I thought.
I'm starting to think that a lot of the problems people are having are caused by keeping NO3 and PO4 too low and starving their corals.
Definitely a must read article. Very informative, thank you.
I'm starting to think that a lot of the problems people are having are caused by keeping NO3 and PO4 too low and starving their corals.
Definitely a must read article. Very informative, thank you.
Well done.
I've personally argued 0 PO4 is not a useful goal for many years.STrip it down and add supplements never appealed to me. I an other s on the chemsitry forum always point out that chasing numbers is poor practice with many of the elements. I prefer to think in ranges . . I do test some things frequently though with full awareness of hobby grade testing's imperfections. I like to try to see changes even with those limits that may occur early on before soemthing bad happens and temper that antsy feeling with patience and discipline not to over react until a trend is at least somewhat clear.
I'd like to discuss a few points and pose a few question about some parts of the article and the thread later on after folks have a chance to read it and digest it if you are amenable.
Thanks for writing it.
I've personally argued 0 PO4 is not a useful goal for many years.STrip it down and add supplements never appealed to me. I an other s on the chemsitry forum always point out that chasing numbers is poor practice with many of the elements. I prefer to think in ranges . . I do test some things frequently though with full awareness of hobby grade testing's imperfections. I like to try to see changes even with those limits that may occur early on before soemthing bad happens and temper that antsy feeling with patience and discipline not to over react until a trend is at least somewhat clear.
I'd like to discuss a few points and pose a few question about some parts of the article and the thread later on after folks have a chance to read it and digest it if you are amenable.
Thanks for writing it.
