Cyano: Symptom of Nitrate Limitation?

[thebanker]

Whenever I test for Nitrates (salifert) they read zero. I'm running a biopellet system.

Occasionally, I have cyanobacteria appearing in random spots in my DT. Could the appearance of cyanobacteria signal a nitrate limitation within my tank's chemistry? (in this case?)

FWIW, I have to actively manage PO4, which likes to creep up unless I change GFO frequently.

 

[whatcaneyedo]

Cyanobacteria is a common side effect of using biopellets. From what I've read and experienced almost everyone gets it at first. It should go away in time... or at least whats what people say. I simply stopped using the pellets.

 

[thebanker]

It's not a pest, but I've had biopellets for 9 months. I'm just trying to figure out what exactly is going on in there.

 

[m2434]

"Cyano: Symptom of Nitrate Limitation?"

Yes, cyano can fix N2, so does not really need nitrate. If there is P and no N, it likely has a competitive advantage. Also, there is evidence that certain types of cyano, under certain conditions can function heterotrophically and utilize organic nutrients. To what extent this occurs in our systems is unknown, but I would not be surprised if some cyano is feeding on organic carbon from the pellets. Especially if there is competition and it is useful for it's survival, but I couldn't say with certainty, to what extent, if this happens in our systems. Even if this isn't occurring, cyano can form mutualistic relationships with bacteria and cycle nutrients and other end products. So, your observation does not seem particularly surprising IMO.

 

[bertoni]

It's possible for carbon dosing to change the nutrient content of the water and encourage the growth of some pest or the other. I'm not sure I'd assume that nitrogen limitation is the cause. I might try more GFO, for example, as a way to limit the cyanobacteria. Different tanks seem to respond differently, so some experimentation is in order.

 

[thebanker]

Thank you for that. I'm wondering if dosing KNO3 will do anything to help.

 

[bertoni]

You could try sodium nitrate. I wouldn't dose potassium nitrate since potassium is a small part of the ionic content of saltwater, about 400 ppm, and might build up with dosing. That said, some people are successful with potassium nitrate.

 

[thebanker]

I think KNO3 is easy to find, I believe it's a common FW planted tank supplement. Any rule of thumb here? I'm guessing no, with the redfield ratio being unknown for various strains of bacteria.

Oh boy. Dosing nitrates. Hopefully I don't have a big algal disaster on my hands.

 

[bertoni]

There are a lot of unknowns in nitrate dosing, so I'd just start with a small dose and see how the tank responds, maybe 1/4 ppm for a first shot.

 

[Randy Holmes-Farley]

You mean a nitrate limitation for phosphate removal by bacteria using the organic carbon?

That may be true, or it may be the organic itself which spurs cyano. IMO it is more often the latter, but it may be either. Dosing nitrate may work as it may allow phosphate to be driven lower by bacteria using both and the organic carbon source. So the cyano may die out for lack of phosphate.

Many folks using organic carbon sources need some extra way to drop phosphate, like GFO. I do, or else algae can become an issue.

 

[thebanker]

Yes, Randy that is what I was getting at, but you put it more eloquently. Since I don't know if PO4 removal is being limited by NO3 deficiency, I'm trying to look at biological signs that would indicate NO3 limitation.

I am using GFO, but am looking for some additional help with PO4 control. I don't have pest issues, just looking to attain that mythical oligotrophic "ULNS" - for lack of a better term.

 

[tmz]

I think it's the carbon source and/ or a bit of PO4 possibly with some other organisms less able to use nitrogen in the forms or quantity available . Some species of cyano, lyngbya for example can fix nitrogen but I'm not sure the typical slime we see does so. Dosing some amino acid like aspartic acid may be a more optimal way to source some nitrogen . FWIW , I also run gfo along with vodka and vinegar dosing.

 

[m2434]

Some species of cyano, lyngbya for example can fix nitrogen but I'm not sure the typical slime we see does so.

Tom, see the review Stal et al. 2010, The Ecology of Nitrogen Fixation in Cyanobacterial Mats (Note: this is Ch3 from Hallenbeck 2010 - Recent Advances in Phototrophic Prokaryotes).

Other tropical, O2 tolerant cyano such as Trichodesmium and Symploca can also fix N2. However, regardless, to date, all cyanobacteria mats studied have shown expression of N2 fixing genes, although it can be difficult to determine if it is cyano or other diazotrophs.

Regardless, I suspect, that due to the mutualism occurring in these mats, it dosn't matter, the cyano still likely will have a competitive advantage in low nutrient environments as a result. Also, although anecdotal, I and others have noted over the years that cyano tends to show up after significant attempts at nitrate reduction have occurred and nuisance micro algae has died off.

 

[tmz]

Thankyou for the reference.

I've also seen some cyano growth earlier on in the vodka dosing process in my tank when nitrates were still 5ppm plus which is where they stayed for months before falling to undetecable. The cyano abated as vinegar was added to the mix ,possibly it feeds a more competitive strain of bacteria.

N fixation may be in play in formed anoxic heterocysts or otherwise in oxygen tolerant species or the cyano may just be better than the new bacteria at scavenging whatever nitrogen and phosphate and maybe carbon that is there ,perhaps contributed by waning nuisance algae .

My tanks are well fed twice per day so it's hard to think any nitrogen defficiency occurred or is occurirng but I suppose it's remotely possible. At this point and for over a year with low PO4 there is no discernible typical red slime cyano but there is some some of what appears to be lyngbya that accumulates a as a small floating mat in the sump and a chaeto fuge.

Adding nitrate to balance off PO4 consumption and export is an interesting experiment and I'm looking froward to information on outcomes of this these applications on reef tanks.

 

[thebanker]

Dosing some amino acid like aspartic acid may be a more optimal way to source some nitrogen.

The only aminos I have are in the forms of SeaChem Reef Plus and Brightwell Restor. They're both a mix of amino acids and some vitamins. Gotta double check that though.

Where would I find aspartic acid?

 

[tmz]

Here:

http://www.iherb.com/Source-Naturals-L-Aspartic-Acid-Free-Form-Powder-3-53-oz-100-g/998?at=0

The aminos you have will add nitrogen as well .I would use them if I had them and suspected a nitrogen deffciency.
Corals do use apartate and can't make it themselves. They are capable of synthesizing many aminos. The aspartic acid from a natural foods store is much cheaper than hobby liquid mixtures.

There are a numbr of threads on amminos and aspartic acid ,too many to list but a sech of this forum should give you plenty to read.

Here is a salient post from a couple of years ago by Randy on it:

<table id="post14175856" class="tborder" width="100%" align="center" border="0" cellpadding="5" cellspacing="0"><tbody><tr valign="top"><td class="alt2" style="border: 1px solid #FFFFFF; border-top: 0px; border-bottom: 0px" width="175">Farley
Reef Chemist

Join Date: Apr 2001
Location: Arlington, Massachusetts
Posts: 75,136


</td> <td class="alt1" id="td_post_14175856" style="border-right: 1px solid #FFFFFF"> I do not bother to dose amino acids, but some may be useful. I consider it still experimental. I discuss them here:

The “How Toâ€Â Guide to Reef Aquarium Chemistry for Beginners, Part 2: What Chemicals Must be Supplemented
http://reefkeeping.com/issues/2007-04/rhf/index.php

from it:

http://reefkeeping.com/issues/2007-04/rhf/index.php#15

Supplementing Amino Acids
The deposition of calcium carbonate into intricately structured skeletons is one of the wonders of corals that aquarists marvel at. At the molecular level, corals often guide the precipitation of calcium carbonate with organic materials, encouraging precipitation on some parts of the skeleton or inhibiting it elsewhere. Often these organic materials are proteins that contain negatively charged amino acids, such as aspartic acid. These negatively charged amino acids may interact strongly with positively charged calcium as it is deposited, allowing the proteins to guide the precipitation.

It turns out that some corals cannot make enough aspartic acid to meet their demand, and must get it from foods or from the water. Depending on the species of coral involved and the foods provided to the aquarium, the supplied foods may not be an appropriate source of aspartic acid for corals, and supplemental aspartic acid has the potential to be useful. It might be taken up directly or be taken up by other organisms that are, in turn, consumed by the coral (e.g., bacteria).

I do not presently add any amino acids to my aquarium, but some aquarists do. Those who do sometimes report improvements in the appearance of their corals. I do not know if this is a true cause and effect, or a coincidence, but aquarists might consider dosing certain amino acids. A number of commercial amino acid supplements are available to hobbyists, and some might also be obtained in suitable form from a health food store (beware of phosphate as one of the other ingredients in human supplements).

I don̢۪t have a recommended dose. If you choose to experiment, start with a low dose, say, 1/8 teaspoon (0.5 gram) of solid amino acid or the equivalent amount of a solution, to a 100-gallon aquarium once a week. Then, slowly ramp up the dose, looking for positive or negative effects.

Note, however, that not all amino acids are beneficial. Many may just drive bacterial growth, and all contain nitrogen, so they may contribute to the nitrogenous waste that ends up as nitrate in many aquaria.

Additional discussion of the effects of amino acids and other organics on calcification by corals appears in this article:

The Chemical & Biochemical Mechanisms of Calcification in Corals
http://www.advancedaquarist.com/issues/apr2002/chem.htm



__________________
Randy Holmes-Farley
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