Effects of low nitrates

[Jaybeastin]

I have an established tank that’s about 2 years. I noticed LPS has been receding but my SPS is taken off.

I finally did some testing and I realized my nitrates was undetectable and now I started dosing for a few days now.

What are the bad effects of having low nitrates ?

 

[Reef By Steele Verified Sponsor]

How are your phosphates, corals (at least their zooxanthellae consume nitrates and phosphates (I believe @Randy Holmes-Farley states they prefer ammonia). One concern I see repeated is that bottoming out nutrients can lead to Dino’s. So raising you nitrates and phosphates would be a positive. But do it slowly. Nothing good happens in a hurry.

Dosing live phytoplankton can provide another food source for some corals, but it can also reduce nitrates and phosphates so I would use caution if you want to do this.

 

[Jaybeastin]

How are your phosphates, corals (at least their zooxanthellae consume nitrates and phosphates (I believe @Randy Holmes-Farley states they prefer ammonia). One concern I see repeated is that bottoming out nutrients can lead to Dino’s. So raising you nitrates and phosphates would be a positive. But do it slowly. Nothing good happens in a hurry.

Dosing live phytoplankton can provide another food source for some corals, but it can also reduce nitrates and phosphates so I would use caution if you want to do this.

My phosphate is at .20 with Hanna checker. My nitrate was undetectable a few ago and now it’s at .05 - .10 . I’ve been dosing 5ML brightwell neo nitro in my 90g once a day. I have a small case of cynos and my bubble algae has reappeared before I dosed.

Will adding a bigger fish increase nitrate ?

I think my reefmat is bottoming out my nutrients and I’m not even using a skimmer. I read a few people had this problem

 

[Reef By Steele Verified Sponsor]

Adding more fish can help you to raise nitrates. Just feeding more will raise them.

 

[Randy Holmes-Farley Verified Community Expert]

The "bad' effects on low nitrate are that you do not know if there is enough available N for organisms or not. There may be (from ammonia, particulates foods, etc.), or there may not be.

Having a few ppm nitrate generally ensures that N starvation is not a problem.

 

[blecki]

Bottoming out nitrates doesn't get you dinos in an old tank. It's only a risk in a brand new sterile tank. At 2 years old you should have plenty of microfauna and critters chowing down on those dinos.

Anyway it can be hard to raise nitrate with feeding and not also raise phosphate, you may need to dose enough to get back into balance first. I personally don't like reef mats and wouldn't run one all the time because they are just so incredibly effective they prevent the refugium from doing it's job. If you don't have a refugium, adding one full of macro algae solves so many balance problems I believe they should be standard equipment on all tanks.

 

[jda]

If you are feeding your fish a lot, then you likely have available nitrogen from other sources. If you don't feed a lot, then you don't know.

I always have low no3, but I feed a lot and nothing appears starved for nitrogen since everything grows and looks good.

You can dose ammonium to add nitrogen. It is very likely are more available source of nitrogen, but you still might not register any nitrate on a test kit.

 

[GARRIGA]

The "bad' effects on low nitrate are that you do not know if there is enough available N for organisms or not. There may be (from ammonia, particulates foods, etc.), or there may not be.

Having a few ppm nitrate generally ensures that N starvation is not a problem.

Grasp the need to see nitrates to ensure nutrients exist but wouldn't overfeeding in the presence of bottomed out nutrients not provide the same assurance? Seems for me easier to overfeed and process the affects of the overfeeding than trying to walk a tight range between something and nothing. Going to zero easy enough these days with carbon dosing or overpopulated refugium. Same for phosphates.

 

[Randy Holmes-Farley Verified Community Expert]

Grasp the need to see nitrates to ensure nutrients exist but wouldn't overfeeding in the presence of bottomed out nutrients not provide the same assurance? Seems for me easier to overfeed and process the affects of the overfeeding than trying to walk a tight range between something and nothing. Going to zero easy enough these days with carbon dosing or overpopulated refugium. Same for phosphates.

I don't think i said anything negative about feeding heavy, but unless one is monitoring corals for "look" related to available N and P, I recommend 2-10 ppm nitrate and 0.03 to 0.1 ppm phosphate, despite those values being well above natural levels, because that can be easier to accomplish and maintain.

 

[jda]

For me, it seems that a lot of people want something that they feel is concrete in the form of a short answer. All of the nuance about nitrogen seems lost on most people. You can explain all that you want about nitrate not really being a good source of nitrogen, but they want some just because they have a test kit and the web tells them to have some.

I still like to explain because some do get it, especially with established tanks that could have a functioning anaerobic bacteria population and might never have no3 above 1.0 again (for long) no matter how much they dose. My guess is that this is what is happening in a two year old tank, which is totally fine, makes reefing easier and nothing will suffer if the fish are being fed well... there will always be nitrogen available from fish waste before it becomes nitrate for the anoxic bacteria to consume.

The crazy thing about having 2-10 ppm of nitrate is that you can still be limited for available nitrogen sources if you are not feeding a lot. Your corals are working harder to get nitrogen. However, the hobbyist has the number that they are looking for. Fishless tanks, folks who want to cut back on feeding to lower waste products (no3 and po4), etc.

 

[Randy Holmes-Farley Verified Community Expert]

I agree that any organism using nitrate instead of ammonia has to first convert it to ammonia to use it to make molecules, but I'm not convinced that is necessarily a problem despite it taking effort by the organism to do so. I'd equate that to claiming that everything (lighting intensity and wavelengths, flow, every element concentration, particulate food availability, etc.) must be optimal, or corals cannot thrive.

I'm also not convinced there is any organism we keep that cannot use nitrate if it is available and other N sources they may prefer are not as readily available.

FWIW, I have never seen any sort of study that examines how well corals thrive with only ammonia vs only nitrate as an N source. Do such studies exist?

 

[jda]

FWIW, I have never seen any sort of study that examines how well corals thrive with only ammonia vs only nitrate as an N source. Do such studies exist?

I think that you know that these studies do not exist and likely never will. Lasse, Biom or maybe Hans (or the like) had some links to some studies that showed that not all coral could turn nitrate back into ammonia - these were in the big no3 thread back over the summer. I will see if I can find them later on. There were some links to other studies that showed up to a 70% additional energy cost to the hosts that could convert no3 back to ammonia. For me, the better analogy is that your daily food is waiting for you a half-marathon away - probably fine for the most fit, but could be a declining proposition to those of even middling health.

Anecdotally, I cannot ignore the decades of DSB reefing where nitrates were always undetectable on test kits and corals thrived. The hobby has somewhat shifted away from DSBs and thus low nitrate levels as a result - would you say that things have gotten any easier? Most of the best reefs that I know about are still very much in that old style of super high import, super high export and low residuals maybe 10x that of the ocean... which is 1.0 no3 and .3 po4... which is not far from the bottom part of the range that you recommend.

 

[Roberto Denadai]

I always keep my no3 = 0 and everything has been fine here for 20 years

 

[Randy Holmes-Farley Verified Community Expert]

I think that you know that these studies do not exist and likely never will. Lasse, Biom or maybe Hans (or the like) had some links to some studies that showed that not all coral could turn nitrate back into ammonia - these were in the big no3 thread back over the summer. I will see if I can find them later on. There were some links to other studies that showed up to a 70% additional energy cost to the hosts that could convert no3 back to ammonia. For me, the better analogy is that your daily food is waiting for you a half-marathon away - probably fine for the most fit, but could be a declining proposition to those of even middling health.

Anecdotally, I cannot ignore the decades of DSB reefing where nitrates were always undetectable on test kits and corals thrived. The hobby has somewhat shifted away from DSBs and thus low nitrate levels as a result - would you say that things have gotten any easier? Most of the best reefs that I know about are still very much in that old style of super high import, super high export and low residuals maybe 10x that of the ocean... which is 1.0 no3 and .3 po4... which is not far from the bottom part of the range that you recommend.

I did not read every paper, but I don’t recall any saying corals could not use nitrate.

 

[jda]

FWIW, I have never seen any sort of study that examines how well corals thrive with only ammonia vs only nitrate as an N source. Do such studies exist?

I will look more later, but this paper looks at N from nh4 and no3 and the differences. I have read it in the past and need to read it again, but they seem to find all kinds of benefits from nh4 and plenty of negatives from no3... energy being a big one.

Some of you all know how I don't really like to link studies since folks can take them the wrong way. I also don't know if this place is reliable and their methods are sound - a friend at Scripps said that they were legit. I did read through some of their links which seem solid.

Lots of stuff similar to this...

More specifically, we were able to link oxidative stress, energy deficit and enhanced bleaching with nitrate enrichment only. On the contrary, ammonium enrichment, maintained the stability of the symbiosis under thermal stress by enhancing its energetic status.

Unravelling the different causes of nitrate and ammonium effects on coral bleaching

Mass coral bleaching represents one of the greatest threats to coral reefs and has mainly been attributed to seawater warming. However, reduced water quality can also interact with warming to increase coral bleaching, but this interaction depends on nutrient ...

www.ncbi.nlm.nih.gov

This is my issues as an engineer only playing in a chemist/biologist sand box as an uninvited guest. Takes a smarter person that me to read this and figure it out.

 

[jda]

I did not read every paper, but I don’t recall any saying corals could not use nitrate.

There was one study that indicated that not all hosts could convert no3 back to ammonia. Not all hosts, but some. I will see if I can find it. I do have seen some pretty good stuff that no anemone can do it, but these papers were all about true coral, IIRC.

 

[jda]

Here is a synopsis about long tentacle anemones and ammonium - IIRC, if you can read the whole article they reference or talk about nitrate not being good. The links are more important here since they can take you down a rabbit hole of how useless no3 is to some "coral" compared to ammonium. I cannot get to some of these anymore, unfortunately, and it has been some time since I read some of these.

Ammonium metabolism in the symbiotic sea anemone Anemonia viridis - Hydrobiologia

The temperate sea anemone Anemonia viridis (Forskål) forms an endosymbiotic association with dinoflagellate algae commonly referred to as zooxanthellae. It is now well established that under appropriate environmental conditions, these associations can be autotrophic for carbon. Under such...

link.springer.com

Some studies mean "coral" as just true coral - stonies. When you dive in more, it seems like many softies do not have the ability to convert no3 back to ammonia. When we talk about reef tanks and "coral" most people mean anything, so there is the possibility for some disconnect.

 

[Randy Holmes-Farley Verified Community Expert]

There was one study that indicated that not all hosts could convert no3 back to ammonia. Not all hosts, but some. I will see if I can find it. I do have seen some pretty good stuff that no anemone can do it, but these papers were all about true coral, IIRC.

Is it a problem if only the zoox can do it, and then gives some of the N to the host?

 

[blecki]

How the times have changed... you just have to look at the 'similar threads' below to see it. They are all the same, high nitrates / low phosphates - and hanging out at the bottom 'ultra low nutrient tank solution?' from last month. It wasn't so long ago that ULNS was a standard method (I still run my big tank that way...) and now it's a 'problem' that needs a 'solution'. (The tank in that thread isn't even ULNS, it has measurable phosphate and nitrate)

 

[Randy Holmes-Farley Verified Community Expert]

How the times have changed... you just have to look at the 'similar threads' below to see it. They are all the same, high nitrates / low phosphates - and hanging out at the bottom 'ultra low nutrient tank solution?' from last month. It wasn't so long ago that ULNS was a standard method (I still run my big tank that way...) and now it's a 'problem' that needs a 'solution'. (The tank in that thread isn't even ULNS, it has measurable phosphate and nitrate)

Well, to be fair, the primary ULNS systems (at least historically) made up for low inorganic nutrients by using other sources of N and P, such as amino acids, bacteria from organic carbon dosing, etc.

That is very different than a blanket statement that undetectable nitrate and phosphate are ok. That too was the assumption long ago, matching NSW, and it turned out to often not be a good plan.