Does excessive nitrate/ phosphate slow down acropora growth?

[Acrofiend]

Ive been reading mixed things about this topic. What do you guys think?

 

[blstravler]

I’m just getting back into the hobby after 12 or so years away. Back then everyone wanted nitrates and phosphates at 0 - now everything has changed. I’ve seen a lot of people saying to keep Nitrates at 5+ and Pho’s at 1? Though it seems the same people have algae (GHA etc) then does NOPOX to stop the algae?

I’m doing the same thing now as I did then and everything is fine. Corals (all SPS) are growing fine.

 

[ca1ore]

I guess it depends on what you consider excessive. My tank runs well at nitrates at 40 and phosphates at 0.2. Corals do seem to grow a bit more slowly, but I’m out of space no no biggie to me.

 

[Ike]

I feel my corals grow slower when I let my PO4 build up. I say that, but I have no idea what my PO4 is at the moment...

 

[Daniel@R2R]

I think the answer is definitely "yes" but what's up for debate is how much qualifies as "excessive"

 

[Acrofiend]

Should of specified. Anything over NSW levels.

 

[PatW]

Virtually all reef tanks have nitrate and phosphate levels that are considerably higher than natural salt water. By “considerably”, I mean an order of magnitude. And many reefers have SPS corals growing just fine under those conditions.

From my reading, for healthy corals, you need nitrates and phosphates that register on home test kits.... say about .5 ppm for nitrate and .01 ppm for phosphate.

For SPS corals, many people advise having nitrates under 5 ppm and phosphates under .03 ppm.

Now, I have read that reefers with well established systems run nutrient levels in excess to those above and their corals flourish. By excess, I mean 20 ppm nitrates and .3 ppm phosphates. And I would not be surprised if some people do fine with even higher levels.

 

[jda]

There is no doubt that elevated levels of either will inhibit calcification. There are many peer reviewed actual science on this. However, the rate might not be noticeable to some, other might not have ever seen anything grow before and even more can certainly tell.

Coralline is super sensitive, IME. Elevate a little bit and it slows down a lot. Stuff is a menace at NSW levels.

There are links in RHF's N and P articles to a few of the many scientific studies.

 

[ZaneTer]

There was a study a long time ago that said yes it does slow coral growth but there have been many more recent studies that say it increases their growth rate.

 

[Graffiti Spot]

What studies say it increases growth? Scientific studies or brs type ones?

 

[Ike]

There was a study a long time ago that said yes it does slow coral growth but there have been many more recent studies that say it increases their growth rate.

Studies with Acropora?

 

[ZaneTer]

I strongly remember them being studies on acropora. Please give me a day or two to find them and I will provide links as soon as I can

 

[SeaDweller]

What studies say it increases growth? Scientific studies or brs type ones?

I think there was a guy on YouTube (a member on here too) who went over a published study, possibly peer reviewed. I want to say it was Amro Azul or something like that.

 

[Ardeus]

Maybe this?

 

[infinite0180]

I think there was a guy on YouTube (a member on here too) who went over a published study, possibly peer reviewed. I want to say it was Amro Azul or something like that.

Amro Azul does do those videos on papers he finds... post it here if you find the one your thinking of!

 

[ZaneTer]

Supporting faster growth at higher PO4 concentrations:

Acropora Muricata - fastest growth at 0.5ppm

Effects of phosphate on growth and skeletal density in the scleractinian coral Acropora muricata: A controlled experimental approach

Phosphate contamination can negatively affect corals, modifying growth rates, skeletal density, reproduction, mortality, and zooxanthellae. We determi…

www.sciencedirect.com

Acropora Longicyathus

Google Scholar

scholar.google.co.uk

Supporting higher PO4 but not nitrate:

Acropora Cervicornis

https://www.int-res.com/articles/meps2005/293/m293p069.pdf

I see it as the general consensus is that higher PO4 is very much a good thing leading to healthier and faster growing coral.

 

[jda]

That last article indicates that growth for A. Cervicornis was good when N and P were low in the first period, slowed when N and P increased for a few periods when and then sped back up again in period 4 when N and P were lowered again. This is pretty consistent with every other peer-reviewed study on calcification that is out there. They also injected co2 which is another variable in it's self... this makes sense in an ocean study since co2 is on the rise, but is not a huge deal in our tanks.

Here are Dr. Holmes-Farley's thoughts about elevated nitrate for our aquariums - direct thoughts for our hobby. This is the smartest guy that I know that also know our hobby. I would listen to him...

In addition to the concerns described above relating to the growth of potentially undesirable organisms that may be promoted by elevated nitrate (especially algae and dinoflagellates), corals can be impacted by nitrate. Many corals may not be bothered by elevated nitrate, or may even grow more rapidly with the readily available nitrogen. But in certain corals, especially those that calcify, there may be negative effects from elevated nitrate.

In most cases where nitrate levels have been examined in relation to the growth of calcerous corals, the effects have been reasonably small, but significant. Elevated nitrate has been shown to reduce the growth of Porites compressa (at less than 0.3-0.6 ppm nitrate),16,17 but the effect is eliminated if the alkalinity is elevated as well (to 4.5 meq/L). One explanation is that the elevated nitrate drives the growth of the zooxanthellae to such an extent that it actually competes with the host for inorganic carbon (used in photosynthesis and skeletal deposition). When the alkalinity is elevated, this competition no longer deprives the host of needed carbon.17

A second study on Porites porites and Montastrea annularis tends to support this hypothesis. They showed that elevated nitrate caused an increase in photosynthesis, in the density of zooxanthellae, and in their chlorophyll a and c2, and total protein, while skeletal growth decreased considerably.18 This effect may not be generally true, however, since elevated nitrate does not appear to have decreased calcification in Acropora cervicornis (though the experiments were carried out under very different conditions).19

One very recent study 20 on Porites cylindrica has reported that elevated nitrate (0.9 ppm) did not increase the rate of photosynthesis or zooxanthellae density, but actually decreased it, contrary to the previous literature. They do not provide an explanation of why their results were different, though they indicated that the corals may have been expelling zooxanthellae, which would confound some of the results. Additionally, all of the corals in the study were stressed in that they lost significant biomass during the study compared to when first collected in the wild. Because of that effect, I do not put much faith in how this study may relate to aquaria where corals are growing rapidly.

Aquarium Chemistry: Nitrate in the Reef Aquarium

This article provides background on nitrate in the ocean and in aquaria, and describes a number of techniques that aquarists have successfully used to keep nitrate levels down to more natural levels in reef aquaria.

www.advancedaquarist.com

...and with elevated phosphate... again, for our hobby, not an ocean study:

One important issue relating to elevated phosphate in reef aquaria has to do with the inhibition of calcification by phosphate and phosphate-containing organics. Phosphate is known to inhibit the precipitation of calcium carbonate from seawater.2-4 The presence of phosphate in the water also decreases calcification in corals, such as Pocillopora damicornis5 and entire patch reefs.6 This inhibition is likely related to the presence of phosphate in the extracytoplasmic calcifying fluid (ECF), where calcification takes place in corals7, and on the growing crystal's surface. Exactly how the phosphate gets into the ECF isn't well understood.

This inhibition of calcification takes place at concentrations frequently attained in reef aquaria, and may begin at levels below those detectable by hobby test kits. For example, one research group found that long-term enrichment of phosphate (0.19 ppm; maintained for three hours per day) on a natural patch reef on the Great Barrier Reef inhibited overall coral calcification by 43%.6 A second team found effects in several Acropora species at similar concentrations.

Organic phosphate and phosphonate inhibitors of calcification have also been studied and probably work by a similar mechanism. Etidronate, a bisphosphonate that is used to treat osteoporosis (Figure 3), caused a 36% inhibition of calcification in Stylophora pistillata at 2 ppm, and stopped it completely (99%) at 100 ppm, while photosynthesis was not impacted at these, and higher, concentrations (indicating it is not a general toxin).

http://reefkeeping.com/issues/2006-09/rhf/index.php#5

 

[ZaneTer]

I’m not sure I see how you think that the articles suggest that higher PO4 leads to lower calcification.

Would you mind explaining?

All relatively recent articles are fairly critical of Nitrate levels but certainly aren’t pointing a finger at phosphate as being a direct growth inhibitor.

As for Dr Farley, I too have a great deal of respect for him but as a man of science he himself has on occasion mentioned that more recent data goes in opposition to that article he wrote many years ago.

 

[vetteguy53081]

I say Yes, at least does not contribute to good growth or color.

 

[ZaneTer]

I’m going to go with “I don’t know”
Not enough research done and what is out there is often conflicting.