Nitrates and phosphates - what does the latest science say?

[Cabinetman]

I always struggled with nitrates and phosphates until I got a denitrator and started dosing lanthanum chloride. My nitrates were 50-100 and phos was sometimes over 1 but I always had a nice looking tank of mostly lps and softies. Once I got the denitrator and lanthanum going my phos dropped to basically 0 or slightly above and my nitrates about 1 which I thought was the best but my coral seamed to struggle. Now I try to keep my phos at between .08-.2 and my nitrates anything over 2... the denitrator keeps them low. I adjust my dose of lanthanum. Since getting in this range my coral is doing way better. I concider your highs to be just that but your average In my opinion is the sweet spot. Watching your video and hearing your experience just solidified my belief. Thanks!!

 

[dwest]

I kept tanks for 6-7 years from the mid-90’s through early 2000’s and never worried much about testing nitrates and phosphates, never dosed carbon, and my tanks looked great. Before I got back into the hobby about 14 months ago, I did a lot of research to “catch-up” on what I had missed or forgotten over the last 15 years or so. There was so much emphasis on maintaining low nutrients, I setup my new tank to be low-nutrient friendly. I even bought an extra dosing pump, assuming I would have to start dosing carbon 2-3 months in. After a while, I noticed I wasn’t getting much growth in my lps or zoas, or even coralline. The zoas also didn’t open very large, and even my chaeto stopped growing and was looking pale. The tank looked sterile... like the frags had been preserved instead of living and growing. I finally wound up with a bad case of dinos.

After following the advice to raise nitrates/phosphates from the long dinos thread, I noticed that my corals started spreading and growing, and the color was a lot better. I also saw that my zoas were opening up a lot bigger than they ever had. Coralline started growing and so was my chaeto. I’m not where tenurepro is as after I traded dinos for hair algae, I ignored nutrients for too long. The dinos came back but not as bad, and I addressed it a lot quicker. Even with the hair algae and 2nd round of dinos, my corals are still doing great, including my sps frags. I believe keeping nitrates/phosphates at decent levels might be as important as keeping ca/alk at proper levels. I don’t believe you can really set standard nutrient levels applicable to all tanks because you are always just measuring what hasn’t been taken-up by the life in the system. In other words, one could measure undetectable nutrients when in reality, considerable nutrients are being taken-up, or one could measure undetectable nutrients because there just aren’t any nutrients. Since you don’t really know what is being taken-up, keeping phosphate at maybe .05 ppm - .15 ppm and nitrate at maybe 5 - 15 ppm, probably insures that there are enough nutrients, but not so high as to cause other problems that can’t be addressed with a decent CUC.

This is eerily like my story as well. Except all my sps died....

 

[redpine42]

Thanks. Always good to step out of the box. A lot of the information on Nitrates and Phosphates, remind me of the old medical beliefs that eating fat, made people fat. We now know through scientific research that is not true and mechanism for people getting fat is understood.

To give a simplistic explanation that Nitrates and Phosphates are bad fails to understand the full biology going on and is more correlational junk science.

 

[tenurepro]

Hi All, just a few collective responses to the comments above.
1) this is a meta analysis - authors looked at a large number of articles to summarize the overall effect of enrichment on coral growth and photobiology. The different studies used different levels/amount of enrichment. So, this is not a useful paper from a sense of finding out the exact thresholds of chemical (i.e. ppm in your tank water). Nevertheless, the power of this sort of analysis comes from looking at effect sizes from multiple studies -> each study may have had some shortcomings and biases, but looking across 40 or 50 studies gives you a very good idea of what the 'big picture' looks like
2) If you are looking for more info on the different studies that the authors analyzed - check the free supplement.
http://www.esapubs.org/archive/ecol/E095/174/
here is the link for the table showing the different experiments and amounts of N + P representing the enriched condition
http://www.esapubs.org/archive/ecol/E095/174/appendix-A.php
3) looking over the levels in the supplementary table - it is safe t say that they are no where near the toxic limits of N + P; So yes, please don't expect a linear increase between P and coral growth; Like with almost everything else, there is going to be a range where molecular is beneficial, above which it starts to become toxic.
4) One important point for me: There was a couple of old studies that have documented big reductions in calcification rates under P enrichment; these studies are commonly cited reason of why we need to keep phosphate at near zero levels (e.g. check out the Calcification Inhibition by Phosphate section in Randy's Phosphate article). Well, the metaanlaysis clearly slows that P enrichment has a significantly positive effect on coral calcification; so the community was somewhat misled by a couple of studies that are not representative of the wider scientific evidence.

thanks all for providing feedback!

 

[Scrubber_steve]

Thanks. Always good to step out of the box. A lot of the information on Nitrates and Phosphates, remind me of the old medical beliefs that eating fat, made people fat. We now know through scientific research that is not true and mechanism for people getting fat is understood.

To give a simplistic explanation that Nitrates and Phosphates are bad fails to understand the full biology going on and is more correlational junk science.

Of course no one would eat a diet of pure fat.
Corals need some PO4 NO3, but too much is as bad as not enough.

 

[Brew12]

Well, the metaanlaysis clearly slows that P enrichment has a significantly positive effect on coral calcification; so the community was somewhat misled by a couple of studies that are not representative of the wider scientific evidence.

I'm not sure I agree with this assessment for a few reasons. I feel the only thing that is shown is that "some" level of nutrients are important to have. I do not think that it shows P will not inhibit coral calcification at high levels.

My reasons for this.

• No mention of alkalinity levels or lighting levels is analyzed yet we know both play a role in nutrient levels.
• Different corals were used in the studies and not every coral has the same nutrient requirements.
• Some studies listed have an "enriched" NO3 and PO4 level below the reference levels in other studies used.
• The same nutrient sources were not used in each study. Ammonia/ammonium, nitrate and nitrogen all take different energy levels for coral to process which can impact growth.
• Units matter. These studies are done in terms of micromoles per liter. Phosphorus has a molar mass of roughly 31. When you see these studies show 4 for phosphorus enrichment that is still only .13ppm and well below the 2ppm other studies show calcification is inhibited. The only study referenced where enriched levels are above 4 was at 26 which is 0.8ppm.

Edit for clarification: 0.13ppm of phosphorus is 0.4ppm of phosphate. 0.8ppm phosphorus is 2.4ppm phosphate.

 

[Brew12]

In an effort to further this discussion I read the results of the one study where phosphates were above 0.13ppm
"Experimental Responses of Panamanian Reef Corals to High Temperature and Nutrients" Juan L. Mate, 1997

Three corals were studied. Pocillopora Damicornis, Psammocora Stellata and Porites Panamensis. No testing was done only increasing nutrients. What they found was that increasing temperature reduced the growth rate of the Psammocora but did not impact the other 2. When higher temperatures were combined with higher nutrients both the Psammocora and Pocillopora had their growth rates significantly reduced.

Rather than disproving anything regarding high phosphates, I feel this does the opposite.

I'm going to go back and edit my previous post to reflect one additional conversion. I did moles per liter but left it in terms of ppm P where we hobbyists tend to use PO4.

 

[hart24601]

It seems to me that most forums now the near universal recommendation is to have some nutrients in the system. I would be surprised to find any thread from this year when the majority of reefers suggest to have 0 phosphate and 0 nitrate unless perhaps there was a very specific problem with a system. I want to say it was around 4-5 years ago give or take when we really started noticing nitrate was needed by a lot of people in the hobby which was seen more en masse with zeo and carbon dosing becoming more widespread a bit before this. Of course these issues have been around longer, but it takes a considerable amount of people before reefing trends are impacted.


Nitrate at this point seems to be the nutrient that impacts tanks more when depleted, but it will be interesting to watch how the hobby goes and if it’s determined phosphate above .05 has advantages in our systems. Sure there are people that have run considerably higher, however it’s pretty low numbers and at this point I think it’s an open question of if their tanks did well because of the elevated phosphate, or despite it.


Many times this hobby has a very reactive approach, many many people found with low nitrates color washed out, so the pendulum is going the other way. The mentality of if a little bit is good, then a lot is better! I don’t think we have quite seen that with nitrate and phosphate yet. Clearly we need some in our systems though. Personally I found I had the best coloration with mari colonies when keeping phosphate at 0ppb and just a hint of color on nitrate test. One must keep in mind I fed like crazy, and directly fed coral too so plenty of phosphates were present, but once the levels hit .03 they browned out – enough I could tell when my export needed attention. Now every system is different, and perhaps the brown mari would grow faster brown, but taking months to color up wasn’t something I wanted to repeat.


But back to the point, I don’t think any experienced reef now would recommend 0 N&P.

 

[sghera64]

Thanks for sharing. My simple take-always:

N or P: not simply good or bad.

Fish Pee: good

Man Pee: bad

 

[User1]

Thank you for the video

This is another tank that was running at PO4 levels around 1.5 - 2 and total unknown NO3 levels (probably very high - never measured at all). When I try to reduce the nutrients levels a little (and start to dose trace elements) I crashed the tank and it was put down in late 2015


My current tank run at PO4 levels between 0.04 - 0.1 and NO3 levels around 0.25 - 8. I dose both PO4 and NO3 on a daily basis


The reason why I construct my new tank in order to take away both PO4 and NO3 in an effective way - indeed so effective that I need to add both PO4 and NO3 was that I was concentrate around the nutrient flux. When I need to add these compounds - I have total control over this flux - the measurement of the water concentration is only tell me how much that is not consumed - if it raise - I add to much - if it decrease - I add to little. This will also mean that the levels will vary - but I think that this is exactly what´s happen in the wild with upwelling ad other similar events.

This is a very interesting article about this

https://www.nature.com/articles/d41586-018-05355-y

https://www.nature.com/articles/s41586-018-0202-3

Sincerely Lasse

@Lasse I believe I've already said this in another thread whereas you posted a clip - love what you have done with your tank. Really well done. Great fish and coral selection with an artistic touch on the aquascape and flow.

 

[Flippers4pups]

I do think we are skipping a very important piece of the puzzle by not including bacteria and bacterial strains within our systems, when discussing elevated nutrient levels.

The direct impact at any given time on these bacteria overall, but also on the strains that reside on and around our corals. Good and bad.

I apologize, I haven’t read the white papers provided above yet, but are there studies that have included what I’ve stated above?

 

[User1]

Warning! Dana knows of Richards tank and how he reefs, at home, but here’s a video from Macna 2017.

Ladies and gentlemen, I give you......

Mr.Richard Ross and his way of reef keeping. His presentation does cover elevated nutrient levels, a little.

There are several interesting points here that he raises but one in particular that I've always wondered about. And that is the turnover rate through the sump. This is something that I've often wondered about with regards to the skimmer. Over flow into the skimmer, skimmer picks up what it can, dumps either into next chamber or flow area that goes into the next, then return pump back to tank (on a simple level).

So this thought process is to flow just enough through it to maximize the skimmer processing?

 

[DesertReefT4r]

Its so funny how things evolve as hobbyists learn as a whole. No more the 5-10 years ago ULN=near 0 no3 and po4 was what was preached as a must for reef tanks especailly sps reefs. Whole dosing systems have been created to support the ULN theory, vodka dosing, bio pellets all to create that ULN sysyem. Most tanks I saw with ULN had very pale corals, alk swings or higher alk would cause burning and TN issues, it was a thin line to walk. I tired the ULN method using vodka then bio pellets and had issues because my water was too clean. Lose of color, browning, once healthy corals died, STN. Now we are back to the idea that some nutrients is needed and corals do much better and better color.

 

[Lasse]

Thanks for sharing. My simple take-always:

N or P: not simply good or bad.

Fish Pee: good

Man Pee: bad

For the book - salt water fish do not pee because of osmotic reasons (or pee very, very, very, very little). The surplus nitrogen will enter the water trough both active and passive pathways by the gills. The secretion is in the form of NH3/NH4 (NH3 as passive secretion - NH4 as active secretion) . The surplus phosphorus will be brought out from the body as faeces. Mostly organically bound P. In order to be in the inorganic form (PO4) - the faeces need to be broken down by bacteria. This will create a time laps between the release of surplus N and surplus P.

In an established aquaria - it does not matter - but in a newly - from scratch started - aquaria this have some importance. When I start an aquaria from scratch - I feed my pilot fish with not rinsed frozen adult artemia. As a part of the conservation process - PO4 is sometimes used for frozen food. In order to ASAP get a nutrient balance in a newly started aquaria I normally use both this trick (to add PO4) and I´m adding NO3 too. I´m strongly argue against using NO3 or PO4 removing processes in the upstart. The bacterial ecosystem has to be established before starting any nutrient controlling programmes. This is also the reason why I think the idea of "cure" expansive living rocks (or dry rocks) is insane and only waste of money and time.

Sincerely Lasse

 

[Lasse]

@Lasse I believe I've already said this in another thread whereas you posted a clip - love what you have done with your tank. Really well done. Great fish and coral selection with an artistic touch on the aquascape and flow.

Thank you

Sincerely Lasse

 

[Sallstrom]

I'm surprised to see that many comments in threads about GHA and Cyanobacteria saying you need to lower the nutrients as the first advice. And that many newcomers say - "now I have reached zero phosphate and nitrate, now what?"
There seems to be some "manual" somewhere saying that you need to have very low nutrients in a reef tank to get good results. I thought that "manual" was changed by now

My guess is if you do a meta analysis of the causes behind the threads about algae and Cyano issues, the most common reason would be too low nutrients or lack of clean up crew. But that's just my guess

So how do we change this "manual"? Who's writing a book? When is your book coming @Lasse

 

[Lasse]

So how do we change this "manual"? Who's writing a book? When is your book coming @Lasse

Never ever - a book is written in stone - an internet forum is always in its move and you always get new angles and insights. But you have to stay put on ecological principles - how in hell can compounds needed in a photosynthetic process become a poison? What you read in your tests is the left over - the not used part of the actual compounds - the left over can be to high but that´s is not the same that there is no consume or need of the compound in question. If I will be served 5 potato at a restaurant and only eat 4 - the dishwasher can´t come to the conclusion that this crazy swede do not like or need potato at all. But that´s exactly what we do when we discuss the measurements in our water column. We have to think in nutrient flux - not in nutrient left over- The ideal situation should be that we exactly know the flux and add exactly that amount every day keeping the left over constant around zero. This is impossible - therefore it is practical with left overs in levels that is measurable safety.

Sincerely Lasse

 

[Stigigemla]

There is a few things I miss in this discussion.
First of all: Corals are different. In the nature you will not see a low nutrition specialized Acropora near a river where the nutrition level is high.
Second: Stable values. Now we know that it is important to hold the big 3, KH, Ca and Mg stable. I believe thats valid for Nitrogen and Phosphorous too.
In a Nature reef there is an influx of water all the time (at least in a square foot dimension) which means that even if the values of N and P are low they are never zero.
In a tank with ultra low values they are fluctuating much more. If you keep the values a tenfold or more over the consumption the value will be pretty stable.

 

[Lasse]

In the nature you will not see a low nutrition specialized Acropora near a river where the nutrition level is high.

Or is the murky colour and lower salinity (read - lower calcium and alkalinity) that cause light demanded fast growing corals not to thrive? You do not know this.

Stable values. Now we know that it is important to hold the big 3, KH, Ca and Mg stable.

Do we really know that? There is indications that stability is a key factor in ULN systems - but what´s about other systems. Because of different reasons - my calcium concentration and alkalinity has vary a lot. Have not seen any negative response of my stony corals. OK - I do not have this unique dream of the dream acropora but a rather good mix of different corals.

Once again - what do we really measure? We measure the left over, the waste, the not used molecules. If we measure 0 - it does not mean that there is no nutrients in the system - it only means that the consumption is larger than the production/nutrient leakage. If there is a constant feeding when you measure 0 in PO4 - the growth of the corals will rise the consumption of PO4. After a while you will have a starving population of corals - hence a stressed population and you will run into problems. In order defeat such an event - a small left over is a safe way to handle it. A readable concentration will give you some time to react if the flux will be to low.

Sincerely Lasse

 

[tenurepro]

In an effort to further this discussion I read the results of the one study where phosphates were above 0.13ppm
"Experimental Responses of Panamanian Reef Corals to High Temperature and Nutrients" Juan L. Mate, 1997

Three corals were studied. Pocillopora Damicornis, Psammocora Stellata and Porites Panamensis. No testing was done only increasing nutrients. What they found was that increasing temperature reduced the growth rate of the Psammocora but did not impact the other 2. When higher temperatures were combined with higher nutrients both the Psammocora and Pocillopora had their growth rates significantly reduced.

Rather than disproving anything regarding high phosphates, I feel this does the opposite.

I'm going to go back and edit my previous post to reflect one additional conversion. I did moles per liter but left it in terms of ppm P where we hobbyists tend to use PO4.

Thanks @Brew12 ; certainly there is some papers that have pointed out -ve effects. But the metanalysis looked over 13 independent studies and found that, on average, P enrichment has a positive effect. While i agree that 'enrichment' may have meant different values in the meta analysis, i don't think it is appropriate to pick a single study of a two species in a a single ecosystem and use that to draw strong recommendations for the hobby to follow.