Theory on BGA/cyanobacteria causational factor/eradication

[jeremy v]

Hello,

I have been thinking about the current understanding of why BGA/cyanobacteria occurs and what to do about it. The current methods are to dose more nitrate, 3 day blackout, lots of water changes, cleaning, and/or medicate the tank to kill it, etc. It seems that often though, these methods are met with only limited success, and to be honest a blackout or medication of the tank to kill it seems extreme to me.

I have a hypothesis as to a possible cause. It is that a slightly anaerobic substrate might be the main or possibly only cause. Now I will explain why I am thinking this so I can get all of your input or correction.

It has been established that BGA can thrive in a low nitrate environment because it has the ability to use atmospheric nitrogen as nitrogen source, and the rest of algae and plants can't do that.

That always seemed off to me initially, because that (in my mind at the time), would only explain BGA growing at the water surface, not down in the water. I looked into it further and found that using atmospheric nitrogen doesn't mean that it needs nitrogen from the air, but more specifically that it can use N2, which is the form of nitrogen found in the atmosphere. N2 is also dissolved (in varied amounts) in aquarium water at all times, and that to me was a key to the puzzle.

What caught my eye a few days ago when I was reading about anaerobic substrates and anaerobic bacteria, was that the bacteria that live in anaerobic substrates actually use nitrate as their food source and give off N2 into the water as their byproduct.

You can have low (or no) measurable levels of nitrate in the aquarium water and still have varying levels of nitrate in the substrate.

If BGA doesn't particularly care about nitrate dosing you would think it shouldn't increase its' growth when nitrate is dosed, but when I tried just dosing extra nitrate to my tank to get the BGA to go away, it actually got worse. What if that increase in BGA growth had nothing to do with the nitrate itself and everything to do with the added nitrate then feeding a slightly anaerobic substrate bacteria more of what it wanted and then having more N2 put out into the water as a byproduct? The aquarium water N2 level might actually be what causes the BGA to begin/increase.

I was thinking about this, because if I dosed the extra nitrate right after a good gravel and tank cleaning (a cleaning of all possible anaerobic zones in the substrate) the BGA didn't really respond to the nitrate addition at all (or at least it was heavily delayed by at least a few days), but if I didn't do that cleaning first it would sometimes double or triple in mass within 24 hours. Could that be the true key to the cause of BGA and its' eradication, making sure the substrate stays as aerobic as possible to keep dissolved N2 as low as possible in the water? Now I give it to you all for your thoughts and experiences to see if they fit or refute my hypothesis.

This hypothesis would also explain how it is said that BGA thrives in poor circulation, but that people (of which I am one) can actually have a small BGA outbreak spot in an area of the tank that has great circulation and well aerated water. It is not the specific spot that is the key, it is the fact that somewhere in the tank anaerobic bacteria is adding extra N2 to the water and that is feeding it no matter where it is located.

As I have said before, I am just trying to figure this stuff out, and I don't know too much about it all yet, so if I am making a wrong assumption in anything I have said let me know. If anyone else has already mentioned this I apologize. I have not read or found anything like this online in my searches so far, but I could have easily missed it.

Have a good one, Jeremy

 

[tedr108]

I hope you'll bump this thread when Tom gets back. I can't answer your question, but thought that I would give some input.

A quote from Tom on BGA prevention:

Maintaining good levels of NO3, 10-30ppm all the time will prevent the BGA, along with routine water changes, good pruning and good cleaning of filter and the tank from now on.

Prevention is the best method.

I think the key word here is prevention. Once the BGA is established, it is a tough customer. It seems that established BGA does not respond to NO3 additions, as you have also noticed. Your theory may be correct, because Tom's conditions of prevention above may very well eliminate anaerobic areas in the tank, thereby eliminating anaerobic bacteria. If your theory is right, I'm certain that good CO2 would help prevent BGA, since the plants will pearl more and help reduce anaerobic areas. Dusko's "Basic Algae" article lists excess organic loading as a possible cause for BGA, so good tank maintenance also removes that as a cause.

I just started some non-CO2 tanks. Typically, a non-CO2 tank would not have 10-30ppm NO3, and also you do not do water changes. Hey, wait a minute -- a non-CO2 tank is not fulfilling a very high percentage of Tom's no-BGA conditions! So now I'm thinking that I had better make doubly sure to prune old leaves and clean the filter and tank well. I get a little lazy about that with my EI tank and have gotten away with it. It's good to get this reminder.

 

[Carissa]

Jeremy,
Your theory does fit perfectly what I experienced.

My initial foray into planted tanks started with a 10g that developed major, major bga issues. It didn't seem to matter what I did - it came back every time and choked off my plants, even though the portions of plant that didn't get covered by bga seemed to be growing well. Incidentally, I had about 2" or maybe sometimes 3" of gravel, really quite a lot for that sized tank. I would gravel vac it, but the bga just kept coming back. Finally I just removed my lighting and waited for my plants to die and gave up. To my surprise, my java ferns took off. I guess they were happy that they weren't being choked by bga anymore. With the insanely low lighting, bga couldn't really grow. I turned my lights back up (to 1.5 wpg) but bga just kept coming once again. Just coincidentally, I decided to change out my substrate, with no thought to how it would affect the bga. I replaced it with a much shallower layer of gravel. Within a week, the bga was gone and never came back. The only places I get bga now are on filter outflows where they are very close to the lighting, also exposed to the atmosphere to some degree like on a hob, and it never spreads.

 

[Koen_v_V]

Hi,

Interesting article, I have same experiences.

My second BGA infestation within 4 months I just killed with anibiotics. CO2 was low for a few days because the bottle ran out and the days before taht I introduced my bought fish to the tank and introduced fish feeding). My tank (500 liters / 130 US gallons) was running on a small eheim (2216) with a fluidized sand bed filter, very good water flows and a lots of plant growth. GBA was spreading like crazy at that moment, and turning on CO2 wasn't helping anymore and almost every plant was covered in it. Water changes of 50% in 4 days wasn't helping and I didn't want to turn out the light (150 watts of T5) for a few days.

In holland it's common to have GBA in small highlighted, aerated spots with low lovel of NO3. But GBA on the gravel and deep levels in the tank are more likely caused by bad nitrification, lots of organic polution (overfeeding), GBA close to unaerated parts of the tank. Well, thats what experts say over here. Startup of tanks with not the right conditions like mine weren't helping preventing an outbreak.

The last to weeks I introduced a second Eheim (2218) and better filter medium cleanup, Excell like (EasyCarbo) and antibiotics and now hope that mecanic filtration and restoring nitrification processes will prevent another one.

 

[yme]

I just killed with anibiotics

how did you obtain the antibiotics?

groetjes,

yme

 

[guy tillmans]

You can use erythromycine 600 mg/300l or 80 usG. once. If needed , dose again after 1 week. I once had bga , after this therapy they never came back. Where you get the antibiotics? I got it from the hospital where i work.

gr guy

 

[defdac]

I brought this exact subject up 2005 at APD:
[APD] Re: BGA, N2 gas and heterocyst

It was a big no from Tom Barr since the fresh water Cyanobacteria that we have in our tanks don't have heterocysts and thereby can't fix N2.

I don't think I got an answer on the question I asked in the above message.

It seems fresh water Cyanobacteria can form very tight colonies and inside create an anearobic environment where they actually CAN fix N2 without heterocysts.

And if so, N2 supplement from an anearobic substrate or the air would give our cyanobacteria a nice lead nitrogen wise =)

 

[Tom Barr]

But BGA, at least the species we see, are far far far from being the least bit NO3/NH4 limited in any way.

So there's no need nor advantage in fixing N2 gas.

I think that's the bigger relevant issue here so we ought to look elsewhere.
Low NO3 seems to induce spores to grow faster, but it it does in no way imply that the BGA is Nitrogen limited.

Big difference.

I know of no algae that's limited in our aquariums vs the typical potential limiting levels in natural FW systems.

The planted tanks we have are very rich for all algae.
Limitation is not a factor.

Inducement/germination of spores are.

Regards,
Tom Barr

 

[defdac]

I know of no algae that's limited in our aquariums vs the typical potential limiting levels in natural FW systems.

Good. That is what I'm telling folks in Sweden.

Low NO3 seems to induce spores to grow faster, but it it does in no way imply that the BGA is Nitrogen limited.

This leads me to a simplification I've thought out.

Let's say jumpin oxygen levels and/or jumping NH4-levels is what makes algae really go nuts (start growing).

To me it seems like you can see what kind of algae that will start growing by looking back how you have run your aquarium before the O2-dip/NH4-spike:

*) Unstable CO2-levels - BBA
*) Low NO3-levels and/or high PO4-levels - Cyanobacteria
*) High NO3-levels - Dust algae
*) Low PO4-levels, very good climate overall - Green spot algae
*) High Fe-levels - Hair algae (Cladophora, Pithophora, Spirogyra, Audouinella?)
*) High Urea-levels - Staghorn or Green water

 

[Tom Barr]

Yes, it seems to becoming more clear what induces algae, rather than treating algae like plants that are only growing vegetatively.

The idea about inducement is key.
You also need a control and tank with good optimal conditions prior to the manipulation.

The experimental treatment/manipulation needs to be done on purpose so you know what to look for and what to expect. Otherwise you have a much more difficult time analyzing anything and might wait years for any observations.

I'm not so sure there inducement in a single factor either.
While I've mentioned it many times, I also hold out for a potential other causes, --after all..........there might be more than one cause and there might be several things in conjunction that cause algae to bloom/germinate.

This is reasonable.

Adding more light or less can certainly influence results.
Measuring light and CO2 are difficult. These both play a huge role, far more than all the BS garbage about nutrients............

Yet few aquarist even really critically measure CO2 and even fewer measure light.

So why the focus on nutrients?
I guess it's because the test kits are 5-10$ and the light meters and CO2 meters are very costly.

Yet plants and algae are not one dimensional, they grow due to light, CO2 and nutrients, not just one issue.

So in order to get around such issues, we have to pick a CO2 level, keep it there etc, same for light and know what they are so we can compare to other systems.

Only then can we really build a model that's fairly predictive to what we see in aquariums. We can pick aquariums that are low light, say 100 micmols or less down to 25, 100-250, 250-500 etc. These likely will need to be matched with CO2.
Say stable non CO2 for the lower light, and stable CO2 for the low light as well.
Then a bit higher for the next step and so on............
Now you can start fiddling with nutrients.

Still, for whatever light and CO2 level you chose, each thing must be non limiting.
This rules out confounding issues. Otherwise you have to start all over because you cannot tell what is causing what.

I see all sorts of post about nutrients and few, if any, address such basic issues.
It's sad really.

Because there's very little actually getting done there and the myths just keep coming.

I fight against it and folks poo poo on you

But.........wind bags aside, there are many more that do read the post and understand that what I'm arguing does make sense and has some logic.
That's why, as well as my own personal curiosity, I keep after this stuff.

Regards,
Tom Barr

 

[Tom Barr]

*) Unstable CO2-levels - BBA
*) Low NO3-levels and/or high PO4-levels - Cyanobacteria
*) High NO3-levels - Dust algae
*) Low PO4-levels, very good climate overall - Green spot algae
*) High Fe-levels - Hair algae (Cladophora, Pithophora, Spirogyra, Audouinella?)
*) High Urea-levels - Staghorn or Green water

BBA has some other factors, perhaps aeration, perhaps substrate type(wood /rock seems more prone to recruitment than say most aquatic plant leaves- plant species differences: say Hygro vs Anubias).

But by and large, it's always seemed to be 95% CO2.
I've found no correlation with high PO4 and BGA, some with low NO3, but never PO4 in and of itself. I've had high PO4 for a long time and never much issue. ADA often has a lot of BGA on the gravel edges and in several other set ups, and with very low PO4 and decent NO3.

This leads to the organics and lack of filter cleaning, too much organic forms, reduced flow etc as another cause for inducement.

I have not seen any inducible aspects to Green dust.........yet. I have plenty of high NO3, and no GD. High light, PC's, etc seem to sure help. At low light, it's much less an issue, much like GW.

I can consistently induce GW using NH4 or urea under high light.
I have never been able to induce GW with any other nutrients over enormous ranges.

Same for iron/Fe.

I've not found any relationship with algae and Fe unless it affects plant growth, and then it is indirect.

Staghorn seemed to be a factor of too much fish load. It comes after BBA in succession.

Other factors like pruning, algae eaters, routine maintenance really play huge roles here, we are assuming that those are independent and are addressed, yet we are human. Many things go into this, but the basics of aquarium care, gardening must be addressed before anything is done further.

I advocated test kit use many years ago, but never gave up using large water changes. ADA does not, Oliver Knott, Jeff Senske, most folks that are in the know and are good scapers do this. They also trim and dose and watch their tanks carefully. They too can neglect things, not do water changes, allow the tank to over grow, forget to dose, etc...........and all of them have.

How far can you push things(both directions)?
How well can you re set things if you do neglect things?
How might light, CO2 play a role there?

I wish it where a simple model, but rarely is that the case.
Answer one thing, often 5 more questions appear and then trying to see how other observations fit in is not easy also.

Regards,
Tom Barr

 

[defdac]

I agree on almost all algae battles are due to CO2.

I've not found any relationship with algae and Fe unless it affects plant growth, and then it is indirect.

Yepp, I was talking about indirect.

I meant it isn't that random what algae will show up if the CO2/NH4 goes bad.

This leads to the organics and lack of filter cleaning, too much organic forms, reduced flow etc as another cause for inducement.

Very true. I oversimply this with "low O2" which ofcourse is not the direct inducement but the O2 will be low if you have alot of organics and less flow etc.

But perhaps that is not a good simplification. It's like when folks thinks the low pH kills fish when it is the CO2. With much CO2 you get low pH though.

Indirect is the key here I think. Most Cyano outbreaks with my and friends tanks have gone hand in hand with low NO3 (and low O2 due to organic buildup etc). I understand ofcourse that I will not be able to induce Cyano by direct lowering of the NO3-levels.

But if the tank have been run with very low NO3-levels, low CO2-levels, organic buildup, lower flowrates and then you get a NH4-spike then I don't think it's random what algae will show up. In fact if I could bet my last penny on what algae would show up I would bet Cyano and I would be pretty confident with the odds actually.

The only weak spot in my list would be GDA. I wouldn't bet my last penny on high NO3 + NH4-spike would lead to GDA, but I wouldn't be surprised if it did.

 

[Tom Barr]

I think a good method to give advice really should be very holistic.

Sound bites, Perception, quick one cause solutions really leave out too much that influences plant growth and thereby algae indirectly.

I think we need to be careful in coming up with standard advice. I think it is certainly attainable.............but it needs the other parts, basic care etc, back to basics so to speak.

I think many newbies, even us experienced folks, Amano included, often over look the basic causes and think it's something else. Later we figure it out and slap ourselves on the forehead for being so dumb. No one is different here.
We all are human and this whole business gets pretty complex rather quickly.

However, all is not lost.

We can figure things out if we focus a step at a time, and address new advice as new observations appear, new potential causes etc. But we are not going to figure everything out with some "super test" etc.

1. Emphasis on basics. Very strongly worded.
2. Pruning and maintaining things.
3. Then possible inducement causes for algae..........
4. Time frame for inducement, appearance, aquarium history etc
5. Good observation for CO2, nutrients etc
6. Consider the aquarist own bias in care(who tends a tank better? When it's going well or when there is an issue?)
7. Personal habits

All these play roles, sometimes huge, sometimes they are fine.
All in all, algae is not a simple thing. I am not comfortable trying to simplify it too much. While it might be nice and there's a strong temptation to do so, I just do not think it's wise.

It leaves out too much and there are way too many unknowns. Folks think I know a lot about plants and algae, but the reality is I barely know Jack. And I am aware of it

There is a lot of things I just do not have answers for. I have a few things I know that algae are not induced by......but all the possible interactions? No way.

So each and every person is a separate case.
They need to go down step wise and check and recheck everything, toss out their assumptions and confirm the parameters are right. Attack algae with many little hammers.

So the how is likely easier, the "why"? Nope.

Regards,
Tom Barr

 

[Carissa]

Just as a sidepoint, high PO4 in and of itself can't possibly cause bga or any other type of algae on it's own. Reason being, I recently acquired a phosphate test kit and tested my Excel tank. It's at least 10ppm, maybe higher (that's how high the test kit goes and it turned instantly to the highest reading without having to wait the 3 minutes or whatever it is). I used the test kits on other tanks, it gave plausible readings which were not high, so I don't think it's the kit. In that tank with the 10ppm+ phosphate reading, I have absolutely no bga. I do have minor amounts of gsa. In fact, I've been dosing extra phosphate to get rid of it. I guess that's how I got so much phosphate in the tank.

 

[VaughnH]

I suspect a lot of us have tested the "high PO4" situation inadvertently. I have accidentally dosed PO4, thinking it was NO3, and that adds a lot more than needed. But, when I did I just went back to my regular EI dosing, no water changes, etc. and no algae appeared as a result. I dose about twice the EI recommended amount of PO4 now and have been for several months. I really like have so much less GSA to scrape off the glass.