Nitrates and phosphates - what does the latest science say?

[tenurepro]

Lots of many interesting points here -
@Stigigemla - yes the bit about coral type/taxa was addressed in the met-analysis; the authors did find that effect of enrichment varied with respect to the group of corals under study.
Regarding other parameters, these studies mostly mimicked local sea water conditions in terms of alk/ca/ etc. One point that i would like to add to this 'complexity' is adaptation / acclimation; Do we really expected a 1:1 relationship between how corals respond to nutrients in a natural reef vs. in our reef tanks. My sps have all be aquaculutred in reef tanks for likely 15 years or so. I suspect that the process of artificial selection (we've selected for coral species / clones that do best in our system) or acclimation has resulted in corals that are better able to tolerate our sometimes dirty tanks.

 

[Brew12]

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.

Let's be clear about what I did when looking at this study. I looked at the ONLY study analyzed with a PO4 above 0.35ppm as the enriched level and it showed a reduction in growth. In every other study that this paper looked at, the enriched levels were below o.35ppm of PO4.

It is fair to say that this analysis shows PO4 below 0.35ppm can help boost coral growth as opposed to having a level near or below 0.001ppm.

It is not fair to say that levels above 0.35ppm do not inhibit coral growth. Most studies I have seen show reduced coral growth at 2ppm or higher and completely stopped at 100ppm. Not a single study in this analysis looked at PO4 at those levels.

So yes, I'm a big fan of higher nutrient systems but that is still within reason.

 

[jda]

My apologies if anybody posted this already, but there are real-science peer-reviewed articles and studies linked in Dr. Holmes-Farley's articles of both phosphate and nitrate that show that elevated levels of both do indeed inhibit calcification... on a sliding scale. Like anything, details matter... so type of coral, etc. is a huge deal. Anybody who has seen tremendous growth spurts of coralline algae can get behind this statement... or seen acropora grow faster than they can generate new tissue with low levels of building blocks. However, slower growth is not all that bad for most... who cares if stuff grows half as slow as long as it looks good and does actually grow? I can grow acropora from 1/2-1" frags to touching and outgrowing the tank in 3 years with low levels of N and P... this is not always a good thing since I hate to frag them up and tear them down... but if I elevate to even 5-10N and .1P, it will take 5-6 years, which is still fine.

When you look at tanks with super high N and P, pay attention to how those tanks got there. Everybody loves to link Ross's tank, but it did most of it's growth and building in a different environment than it is in now where it is just maintaining... and he has lost some stuff.

 

[Lasse]

and he has lost some stuff.

As most of the ULN people has done and a some of them have lost more than "just some".

I can grow acropora from 1/2-1" frags to touching and outgrowing the tank in 3 years with low levels of N and P... this is not always a good thing since I hate to frag them up and tear them down... but if I elevate to even 5-10N and .1P, it will take 5-6 years, which is still fine.

Any prove of this statement?

Sincerely Lasse

 

[Amoo]

Yes the links in Randy's paper were mentioned in the video that the OP posted that is a crucial part of this discussion................

 

[Crashjack]

I don’t think anybody can really say he/she has an ULN system because one can only measure the residual nutrients (e.g. those nutrients that haven’t been consumed). If your system generates a decent amount of N/P and your corals and such consume it all, then your testing will show very low levels but in reality, you have plenty of N/P. However, one could just as easily measure low or no N/P after corals and such have consumed zilch.

The difference in my new tank and those I ran 15+ years ago is: 1) This tank was started with 100% dry Pukani rock, 2) This tank was considerably larger than the tanks I ran years ago (my largest in the past was 75 gal, and this tank has a 180 footprint but is only 19” tall), 3) This tank has a decent sized, well-lit refugium full of chaeto. 4) This tank has a much better skimmer than previous tanks. There are also some lighting and other miscellaneous differences.

My belief is that my new tank never built-up and sustained enough nutrients and also likely lacked a wide diversity of bacteria. I’ve also stocked and am still stocking the tank very slowly. My hypothesis is that with such a small amount of livestock to utilize and generate much nutrients, my truly low-nutrient system became a haven for opportunistic dinos, hair algae, and cyano. I now have to stay on top of artificially enhancing nitrate/phosphate levels, presumably until the tank is well-stocked and can generate enough nutrients to support corals and such and to keep nuisance algae and cyano in check.

 

[Thales]

When you look at tanks with super high N and P, pay attention to how those tanks got there. Everybody loves to link Ross's tank, but it did most of it's growth and building in a different environment than it is in now where it is just maintaining... and he has lost some stuff.

The nutrient levels in my tank have been roughly the same since at least 2014- po4 around 1.5, nitrate above 60. I switched to LED's after the amquel debacle in 2015 0r 16, so since then all SPS have been grown in the high po4 and nitrate conditions. The stuff that I lost in the last year was mainly due to a protozoan infection and non reef life driven LARS. The tank seems to now be back on track and growing well - I'll snap some shots when the lights come on. For the last year and half, I have been working on lowering the levels through carbon and Lanthanum dosing, but for the amount of work it is taking to do so, and the apparent lack of change in the corals, I don't know if I will continue.

 

[Thales]

Here is the 2014 article
https://reefs.com/magazine/skeptical-reefkeeping-ix-test-kits-chasing-numbers-and-phosphate/

I just did a quick pass at the video in the OP. Seems great, will find time to listen more throughly.

 

[Stickboy15]

I can’t run my system with anything lower then po4 0.6 and not get stn on acros so my range is 0.6-0.8 and nitrates 5-10

 

[shnapper20]

thankyou, Ive been struggling with my corals since Ive been using a nitrate reactor ie biopellets my nitrates have mostly been undetectable , Ive been dosing nitrate and feeding more this confirms im heading in the right direction. I changed lights before I started using the reactor my corals were doing well and i never measured nitrate. After changing lights ie metal halides to leds my corals started dieing I measured my nitrates and they were above 40ppm. It looks like it may have been the lights and not the nitrates giving me grief thanks for the video.

 

[dave57]

I believe every system is unique in its own way. Trying to replicate someone’s success will not yield you the same results. One must find what works for your system. So replicating WWC or BRS methods will not create that instatank one desires. Every patient can’t be treated the same way. There are however guidelines and specific ranges to maintain for a healthy ecosystem. One must find the range that works for your reef.

 

[Belgian Anthias]

Hi tenurepro, nice video.

My tank once had NO3 at 60ppm plus, & po4 at 3.0ppm (unknown due to bad test kits). That is a dirty tank. Nothing would survive. I initially reduced both nutrients to zero (on home test kits) & things changes immediately, especially the proliferation of coralline algae, which of course is the most easily observed calcifying organism in an aquarium. Presently, my PO4 is 0.03 - permanently, & NO3 fluxuates between 0.25 & 8ppm.
Maintaining nutrients around these ranges is important but many other factors come into play, especially flow & light intensity - duration - spectrum.

cheers.

Just for information:

Coralline algae , growth was limited or increased?

NO3 fluctuates, over what time span are we speaking. To what may the fluctuations be attributed?

 

[Scrubber_steve]

Just for information:

Coralline algae , growth was limited or increased?

NO3 fluctuates, over what time span are we speaking. To what may the fluctuations be attributed?

No coralline growth at all during high nutrient stage.

No3 fluctuated as a result of filtratation unit testing. Under normal operation only slight variation.

 

[Belgian Anthias]

thankyou, Ive been struggling with my corals since Ive been using a nitrate reactor ie biopellets my nitrates have mostly been undetectable , Ive been dosing nitrate and feeding more this confirms im heading in the right direction. I changed lights before I started using the reactor my corals were doing well and i never measured nitrate. After changing lights ie metal halides to leds my corals started dieing I measured my nitrates and they were above 40ppm. It looks like it may have been the lights and not the nitrates giving me grief thanks for the video.

Biopellets in a reactor for denitrification ( very low flow rate) or for assimilation ( high flow rate )? Are you trying to manage the nitrate level by adding more nitrate?
Changing light changes the photo autotrophic activity. If you where happy with algae growth before I would gradually increase light intensity.
I am not a fan of biopellets as they may leak Polyhydroxyalkanoates ( PHA) creating a very high C:N ratio in a system with very low nitrates.

 

[MARK M. DAVIS]

I'm not convinced! Different coral tolerate Nitrates and Phosphates but, SPS and Monti's won't do well with a lot of nitrates (>25). Phosphates promote competing algae which will overgrow and kill the coral. I think with minimal feeding, there will always be some phosphate and nitrate but, not too much. I also use an algae scrubber because nitrates will just accumulate without a good export method. I feed the coral as well, with food, not with stump remover or other additives. I don't believe that anyone said 0 nitrates or 0 phosphates were good but, very high concentrations on each have negative effects that need to be curbed by export. I agree with the FISH poop vs. additives! There's a lot of ways of feeding the coral and zooxanthellae without browning out the coral.

 

[TexasReefer82]

This is a thread topic that I've considered starting myself - glad to see that tenurepro started things off! Thanks for the great video!

I've experienced STN due to phosphate deficiency a few times in the last couple years. I state that cause - phosphate deficiency - like it's a fact because I've been able to stop its progression by dosing phosphate. The last time I saw it (on a colony of Bali green slimer) I first measured with a Hanna ULR and got a reading of 0.009ppm (within error range of zero) dosed 0.1ppm phosphate into the tank and the STN stopped in its tracks. The coral then began to recover within a couple days.

Some interesting observations I've had with Phosphate deficiency - STN:
- Tissue decay/STN on acropora/monti colonies starts as small areas that appear somewhat bleached/miscolored and sickly
- Tissue decay/STN from Phosphate deficiency in my own tank has consistently appeared only on areas of the coral (acropora, Montipora) that are older tissue, that are shaded, or at the crotch/split at the base of a branches(s).
- It never appears on new growth (indeed the tips are typically actively growing with great polyp extension when STN hits the older parts) or on the most brightly illuminated areas of the coral.

My hypothesis is that there exists a reservoir of Phosphorus (and likely Nitrogen too) within coral tissue. It takes some time for this reservoir to deplete in zero nutrient water or replete in high nutrient water. Perhaps this is the reason that low/high nutrient levels in the water column take some time to manifest into problems - either the reservoir runs empty and STN occurs or the reservoir is full and toxicity occur. It's my suspicion that in the case of deficiency/empty reservoir the coral will actively cannibalize itself – stealing scarce phosphorus from the shaded and older parts of the colony to feed the active new growth. This cannibalism can go on for only so long before the tissue is weakened enough for a bacterial infection to set in (STN). The phosphorus clearly plays a role in general tissue health and integrity but I suspect it also plays a role in the production and maintenance of pigments. P's role in pigmentation may be why brightly illuminated are nurtured at the expense of shaded areas.

 

[TexasReefer82]

As mentioned in the video - I completely agree that a sizable and effective clean-up crew is essential.

Presumably, the N and P flux out of the water column and into algae is proportional to the amount of algae mass present. Algae mass must be kept to a minimum mass (i.e. constantly mowed down) to retain nutrients in the water column and leave them available for the corals in our tanks.

How is it that corals acropora/montipora on the wild reef are able to thrive in such low concentrations of nitrate and phosphate? Presumably they're receiving these nutrients from other sources such as plankton or the aforementioned fish poo. Makes me question the utility of a skimmer once the tank has grown some sizable colonies.

 

[jda]

Most tissue degradation in shaded areas is caused by lighting. I have never had death from underneath in any of my tanks and the area continues to encrust and develop. I do think that coral will forsake that area first if it does not have enough energy to survive - energy that comes from sugars from the zoox... which comes from lighting. N and P are needed to build new tissue, but are not used for energy... you need sugar for this.

Throughput is important, not residual numbers on a test kit. Ocean is the same way... heavy import and heavy export. ZeoVit tanks, for example, have nearly undetectable N and P levels yet they have massive input of foods and stuff... but also massive export.

 

[Belgian Anthias]

If phosphate is not good for calcification how the relative high phosphate content in shells and aragonite is explained?

 

[Belgian Anthias]

I do not think that the level of nutrients has much impact if not very high. What is measured is what is is left over. One may have a high daily phosphate production and consumption and a low phosphate level.