Iron, GFO, and Cyanbacteria

[asylumdown]

I know there are threads on this topic lurking around here somewhere, I may even have contributed to some of them. However, I've had recent anecdotal experience that has strongly supported a suspicion I've had for a while now and I am hoping someone who knows more about chemistry and cyanobacterial metabolism will eventually see this thread and offer input.

The question is simple: Can cyanobacteria use the form of iron that is found in granulated ferric hydroxide (AKA GFO)? Are they able to take it up and convert it to whatever form they require to build their photosynthetic structures?

Like many people, I've struggled with cyanobacteria for as long as I've been a reefer. In my current tank, I only started struggling with it when I switched from PO4x4, which is a form of GFO that is encapsulated in some sort of polymer (also expensive and hard to get in Canada) to the more standard granulated forms like bulk reef supply GFO or rowaphos. I started this tank with biopellets, so I chalked it up to them, but the kicker is that my tank ran for 8 months with biopellets with no cyano, and only came down with it when I switched to the kind of GFO that releases large (compared to not using it at all) quantities of iron hydroxide dust in to the tank every time you change the media out. I haven't been using biopellets for most of 2014, and while my tank has faced challenges I'm still not able to completely explain, cyano has been a constant, damaging nuisance.

My recent experience - my house was being renovated for most of August and a good chunk of September. Long story short I couldn't really access the tank beyond feeding the fish and it was exposed to large quantities of porcelain tile and self levelling cement dust. Unsurprisingly, big dollars in coral died. Unknown to me, the pump that drove my GFO reactor also died during that time.

When I was able to get back in my house and start rescue procedures for what survived, I was rather surprised to find no trace of cyano. Not a speck, not a slightly red hue, nothing. Not even on coral skeleton that had been dead long enough to start growing coraline algae (and we all know how cyano LOVES freshly dead coral skeleton). I fixed the GFO reactor and replaced the media... BAM! 24 hours later, traces of cyano on almost everything. Two weeks later, it's a serious problem again.

I know from the scientific literature that cyano, of all the auto-trophs, has a particularly high demand for iron to construct it's photosynthetic structures. I also know that recent research on to 'black reefs' has pretty much confirmed that iron hulled ships wrecking on iron limited reefs can turn vast swaths of previously pristine surrounding area in to dead, black reefs smothered in carpets of cyanobacteria. I also know that the usual advice for people who get cyano is to ramp up GFO use, but I have yet to find a thread anywhere on the internet where that seems to have helped, and have found several threads where people have commented on cyano first appearing immediately after starting GFO for the first time. I have also never really found a serious discussion about the possibility that the iron in GFO, under the right tank conditions, might itself be feeding the growth of cyano problems. In the absence of GFO or intentional dosing, iron limited but "high" nutrient (relative to the ocean anyway) seem to be the default condition for most reef tanks, which are exactly the kinds of reefs that seem to be most damaged by the sinking of iron hulled ships.

However, all this hinges one whether or not the "F" in GFO is in a form that cyanobacteria can do anything with metabolically, which is what I'm hoping someone on here can answer.

 

[Bryopsis]

Given this, I wouldn't think so?(I have no idea, but if it's insoluble~but perhaps it's still changing/breaking down somehow?)

Since iron is a major component of GFO, and this substance is subject to weak grinding action within a fluidized reactor, it might be expected that the iron content of the aquarium water would increase, and indeed it did. Further analyses found the iron to be almost entirely in the ferric form, but perhaps more importantly, as mostly in the form of suspended particulates and not dissolved.
http://www.advancedaquarist.com/2012/2/chemistry

I know from my own experience, it's when I do water changes cyano pops up. (not really any other time, it'll slow go away after the wc)

 

[Dapg8gt]

I'm also a guy who deals with it constantly in some form in my display tank (mostly minor) but it's always present.. If I wait more than 2 weeks to siphon small patches off my sand with my water changes it will spread. All the while running gfo

On the other hand my separate frag system with higher nutrients and no gfo has not one bit of cyano.. I never thought about the correlation of gfo though so I'll be interested to see if it is just a coincidence or its feasible ..

 

[msderganc]

I seem to remember Randy saying that the iron in GFO never gets released into the water.

However, have you considered that it might be an imbalance between nitrate and phosphate? That is, with the GFO online, you eliminate the phosphate from the water, which algae/bacteria need to grow, and the cyano, which is notoriously adaptive, can somehow utilize only nitrate, therefore outcompeting other organisms.

 

[asylumdown]

I seem to remember Randy saying that the iron in GFO never gets released into the water.

However, have you considered that it might be an imbalance between nitrate and phosphate? That is, with the GFO online, you eliminate the phosphate from the water, which algae/bacteria need to grow, and the cyano, which is notoriously adaptive, can somehow utilize only nitrate, therefore outcompeting other organisms.

I've always had an issue with that idea. It's repeated almost as gospel on online forums, but a) the idea of an "imbalance" in this context is a biologically meaningless term. If there's such thing as an "imbalanced" state, what would constitute a "balanced" state? What ratio of dissolved N vs P would trigger cyano and what ratio would inhibit it? As determined by what research or plausible and supported biological theory? It's an idea that seems nice because it explains an otherwise unexplainable phenomenon, but it's not based on a shred of evidence, nor does it have a convincing analogous example from the natural world. Iron supplementation causing massive algae and cyano outbreaks in previously algae and cyano free/limited environments, however, is well documented.

B), Cyanobacteria can fix some degree of atmospheric nitrogen while most other problem algae-like organisms can't. They have to rely on the water or the substrate for phosphorous. If anything they should profit from a low N/high P scenario, not the other way around.

And "not released in to the water" is a tricky idea. What constitutes being "released"? Have you ever looked at the colour and clarity of the water in your gfo reactor immediately after changing the media? Even with exceptionally neurotic rinsing, you're still going to get a cloud of gfo dust that is dispersed around the entire tank. If not continuously, at least within the first few hours. Iron is not inert. Iron hydroxide is not inert. If it was, it wouldn't be useful as a phosphate adsorber. There are a dozen atoms necessary for life that transit through ecosystems in forms unusable to life at some stage. Unusable until some critter with a specific metabolism and a specific set of enzymes comes across it breaks it down and converts it from one state to another, that is. This is the essential foundation of the carbon, nitrogen, and phosphate cycles, why would iron hydroxide be somehow exempt?

It seems unlikely to me that an organism as old and as adaptable as Cyanobacteria would not have evolved a metabolic pathway to harvest, digest, and transform an atom as vital to survival as iron.

There's a pretty sound theory out there that Cyanobacteria are such gluttons for iron because they evolved in a pre-aerobic world, where iron would have been far more available. Iron is an incredible electron acceptor, which makes it pretty much the most useful molecule to do biological work that involves oxygen (ahem, hemoglobin). From an early photosynthesis point of view, this was invaluable. Their insane-balls success altered the atmosphere so drastically (aka, the great oxygenation event), that most/all iron in the ocean and on the surface oxidized into iron oxide forms that were much harder for them to use. But evolution being the messy thing that it is, instead of reducing their demand for iron, Cyanobacteria just figured out better ways of using the forms that were available. It's theorized that this is one of the reasons cyano species use so much more iron in their photosystems compared to groups of autotrophs that evolved later.

Gfo is basically a particular oxidation state of iron oxide. Evolutionarily speaking, its not a stretch to hypothesize it's exactly what Cyanobacteria has spent the last 3 billion years figuring out how to use. Saying it's not released in to the water because it's released as dust particles is like saying a bag of rotting shrimp isn't releasing nitrogen in to the water because the shrimp is a solid, non-soluble object. Bacteria break the shrimp down in to soluble, usable forms. Cyano just so happens to also be a bacteria...

In nature, organisms don't wait until there's some magical "balance" of nutrients to grow. Their growth rate is controlled by whatever nutrient is limiting, and their biomass is controlled by that plus whether or not there is some form of predation or environmental extremes curbing their growth. There is no environmental condition you could maintain in a tank (salinity, temp, etc) that would be harmful to Cyano without killing every single thing you set up the tank to keep, and if you could identify a good cyano predator and breed it, you'd be rich. That leaves limiting nutrients.

Occam's razor suggests that if you add a chemical intended to reduce the level of some nutrient that is itself a potential nutrient to some organisms, and you see a sudden increase, explosion, or sustained presence of said organism, the simplest, most logical, and therefore likely true explanation is that you have not added enough of said chemical to reduce the target nutrient to limiting levels, while adding large amounts of another that previously was.

 

[asylumdown]

I'm also a guy who deals with it constantly in some form in my display tank (mostly minor) but it's always present.. If I wait more than 2 weeks to siphon small patches off my sand with my water changes it will spread. All the while running gfo

On the other hand my separate frag system with higher nutrients and no gfo has not one bit of cyano.. I never thought about the correlation of gfo though so I'll be interested to see if it is just a coincidence or its feasible ..

I'm going to give a GFO free tank a shot for a while. I'm looking in to alternative methods for phosphate control. I should also add that my tank has only a very small lighted refugium, with a minimal amount of macro growth relative to the tank volume, so I don't have much else in the tank with a high demand for iron.

 

[asylumdown]

Given this, I wouldn't think so?(I have no idea, but if it's insoluble~but perhaps it's still changing/breaking down somehow?)



Since iron is a major component of GFO, and this substance is subject to weak grinding action within a fluidized reactor, it might be expected that the iron content of the aquarium water would increase, and indeed it did. Further analyses found the iron to be almost entirely in the ferric form, but perhaps more importantly, as mostly in the form of suspended particulates and not dissolved.

http://www.advancedaquarist.com/2012/2/chemistry



I know from my own experience, it's when I do water changes cyano pops up. (not really any other time, it'll slow go away after the wc)

Is that not when you often change the gfo as well? I usually do it all as part of my weekly maintenance. While I often do water changes without a gfo change, it's rare for me to change gfo without a water change.

 

[dartier]

If you want to try another experiment to see if you can continue the use of GFO and avoid Cyano, try putting a couple of tablespoons of Cuprisorb in a filter bag in your sump. I noticed that my GHA would die off while my NO3 and PO4 remained above what most people would consider too high. I found that I had to dose Iron to keep my corals happy during this period.

Then I stumbled on a thread about Cuprisorb being linked to a treatment for Dinos. That made me investigate what Cuprisorb actually does and it turns out it is a DeIonization media for heavy metals.

At that point I removed the Cuprisorb from my sump and within 2 weeks my GHA came back worse than ever. Now I only do very limited Iron dosing and do not keep Cuprisorb in the sump.

So as a test you may want to see if Cuprisorb can affect the Cyano while using GFO. Just be prepared to be patient as it took a while for my tank to become Iron deficient enough to affect my corals and get me looking for a cause.

Dennis

 

[msderganc]

Here's a great post on the topic: http://www.reefcentral.com/forums/showthread.php?p=11360349

Low iron may actually help cyanobacteria.

 

[Aquarist007]

It could be reducing the phosphates eliminates some organisms that are in completion for nitrates. I always found that nitrates seem to be the driving force for cyano while phosphates the driving force for byropsis.

 

[asylumdown]

Iron, GFO, and Cyanbacteria

Here's a great post on the topic: http://www.reefcentral.com/forums/showthread.php?p=11360349

Low iron may actually help cyanobacteria.

The notion that iron supplementation could "swamp out" the competitive advantage of cyano, which can harvest and use iron in low iron environments requires there to be some other organism in the system that could ramp up growth to compete with the cyano. Unless you've got a huge refugium with tons of macro, where would this competition come from in a small, captive tank?

"Swamping out" the competitive advantage requires another group of organisms to start growing as fast or faster as cyano. In the open ocean, I'm sure that happens all the time. Macro algae and phytoplankton growth probably picks up, and the net effect is less cyano, even though the total biomass has gone up.

In a tank? Where are these competitors? If they were suddenly favoured to the point where they could out compete cyano, you would probably notice, and the posts wouldn't be "argh! Cyano!" They'd be "how do I deal with this other horrible problem algae that's growing from the ashes of my dead cyano population?"

If you take an organism THAT efficient at harvesting iron in a low iron environment, and you put it in a tank with practically no space for competitors, and then dump a ton of iron in to it, you're not going to see an inhibition of cyano. You're going to see the opposite. Inhibition due to competitive advantage would require your tank to be bursting with some other problem algae that was actually doing the competing.

Otherwise, all you're doing is providing a huge amount of iron to an organism with an incredibly sophisticated apparatus for harvesting iron from a low iron environment.

 

[asylumdown]

It could be reducing the phosphates eliminates some organisms that are in completion for nitrates. I always found that nitrates seem to be the driving force for cyano while phosphates the driving force for byropsis.

I suppose it could be, but this quickly goes back to the magical "balance" hypothesis, which is untestable and has little, if any, analogous scenario that's been researched in the natural world.

Which organisms have been reduced? Are they invisible? My tank has as much micro and macro life (that I can see with my eyes or microscope) whether I'm using gfo or not.

 

[asylumdown]

If you want to try another experiment to see if you can continue the use of GFO and avoid Cyano, try putting a couple of tablespoons of Cuprisorb in a filter bag in your sump. I noticed that my GHA would die off while my NO3 and PO4 remained above what most people would consider too high. I found that I had to dose Iron to keep my corals happy during this period.



Then I stumbled on a thread about Cuprisorb being linked to a treatment for Dinos. That made me investigate what Cuprisorb actually does and it turns out it is a DeIonization media for heavy metals.



At that point I removed the Cuprisorb from my sump and within 2 weeks my GHA came back worse than ever. Now I only do very limited Iron dosing and do not keep Cuprisorb in the sump.



So as a test you may want to see if Cuprisorb can affect the Cyano while using GFO. Just be prepared to be patient as it took a while for my tank to become Iron deficient enough to affect my corals and get me looking for a cause.



Dennis

I'll have to look in to cuprisorb a little more. I've never even seen the packaging I don't think. It removes more than just copper?

 

[asylumdown]

Iron, GFO, and Cyanbacteria

Here's a great post on the topic: http://www.reefcentral.com/forums/showthread.php?p=11360349

Low iron may actually help cyanobacteria.

Further - having siderophores that can capture enough iron in an iron limited environment does not mean low iron "helps" cyano. It means that it might not hinder it. What it also means is that when iron levels go up, cyano is uniquely adapted to capturing it and using it compared to other organisms, and can probably do it more efficiently and with more oxidation states of iron than other organisms.

Here's an analogy - a population of animals with a high caloric demand evolves in a food limited environment. They evolve multiple pathways that allow them to capture and store every excess calorie they come across. Times change and suddenly food is plentiful. Those metabolic pathways that kept them alive through multiple famines now lead to morbid obesity.

 

[Randy Holmes-Farley]

IMO, the potential for iron or other trace elements to be limiting to cyano if not dosed or brought in by water changes is an interesting hypothesis.

Whether one wants iron to be limiting is another question, and may vary from tank to tank, depending on what else is present.

I expect some iron is released from GFO, but whether it is significant relative to other sorts of iron inputs, I do not know.

FWIW, I dose iron, and also use GFO. Cyano comes and goes in my tank, but rarely enough to worry me. I've not tried to stop iron dosing and water changes long enough to see if it impacts the cyano.

 

[asylumdown]

Randy you also run a pretty well stocked refugium don't you? I wonder if your tank would be an example of one where there's actually some of that competition I was talking about going on.

I've never really had much by ways of a refugium, this tank has a small one but I only put a light over it a couple of months ago and relative to tank size and the amount of algae it's growing I don't think it does much more than give my tank a place for pods to grow.

I've never not run gfo on a tank. I've also not ever had a tank that didn't struggle with cyano at some point either. It's interesting to me that this tank's first appearance of cyano coincided with a switch from a polymer coated form of gfo to a normal granulated kind, but that could have a couple of other explanations as well. In any case I'm willing to give the gfo free tank a try for a while. I've set up a rather elaborate system to control phosphate with phozdown via a doser and a series of nested filter socks stepping up from 10 micron to 100 micron. I'm starting slow and am testing every day until I figure it out.

 

[Randy Holmes-Farley]

Yes, the macroalgae and other organisms that I have may very well such up iron quite quickly.

 

[jayball]

Just to add to the anecdotes here.

I have never had a big cyano problem in my main tank even though I am overdue for my "new tank" bloom, just a spot here or there that goes away on its own.

I have recently moved the outlet of my GFO/Carbon reactor from the return section of my sump to the second/fuge section (trying to add a little more flow) and after that I had a huge bloom on my rock rubble and macroalge. Nothing in my tank to be found now.

Again this is anecdotal, but I saw a direct correlation.

 

[asylumdown]

well I used lanthanum until early December. There was zero cyano in my tank that whole time, but I was never able to get the dosing rate dialled in. In retrospect, I'm not sure you ever could.

I had to scrape the glass with a razor every few days as the mag float couldn't keep up with the pace at which the algae was calcifying.

I went back to GFO at the beginning of this month, but have been rinsing it far more neurotically than I ever used to. The algae on the glass has gone back to only needing wiping with the magnet every couple of days, and a few spots of cyano have cropped up but they're small enough to spot control with peroxide so far. I just got a shipment of PO4x4 from the states that needs much less rinsing, so we'll see how it goes.

 

[Dan_P]

The amount of extractable ferric ion from GFO should be very, very small. It would not be unreasonable to assume that cyanobacteria can reduce this to the more useful ferrous ion. Is GFO the cause of persistent cyanobacteria growth?

If the hypothesis is that GFO does encourage cyanobacteria in aquariums, no one has done an appropriately comtrolled experiment to support the notion.

Cyanobacteria will be found growing/not growing in the presence of a high level of phosphate or with an undetectable level of phosphate. Ditto nitrate. Ditto iron. Ditto in the presence or absence of GFO, GAC, skimming, filter socks, water changes, flow, light qualty, etc. No one factor can by itself has ever explained the presence or absence of cyanobacteria growth in aquarium.

No one ever leaves cyanobacteria bloom alone, so, we don't know what percent of outbreaks resolve by themselves. When remedies are tried, rarely is only one remedy tried at one time and never is only one change at a time made in the aquarium. We basically don't know why a particular case of cyanobacteria is resolved or in your case not resolved.

The exception to these observations about remedies is Chemiclean. Chemiclean does seem to be a fairly reliable remedy, though not without risk and not foolproof. Lights out might also be useful but it is probably not as reliable a Chemiclean.

It sounds like the cyanobacteria has become a resident in your biological filter or microbiome and that no other organism is going to drive it out. You might try dosing with bacteria to disrupt its current hold. This probiotic remedy though is a new idea and unproven.

You might as well bite the bullet and use Chemiclean. A year is a long time to deal with cyanobacteria.