Possible Conditions Favoring Cyanobacteria Growth

[Uberhoust]

Most of us that have raised fish at one time or another have run into an issue with cyanobacteria, myself included. Frequently a number of people suggest that we are out of balance or that we have too large of a nutrient load in our aquariums. Conversely there is some anecdotal statements that the cyanobacteria growth is encouraged with decrease nitrate in the water with some on the reef and planted aquarium sites suggesting adding NO3 to the tank to help. These statements are often not helpful because they really don't help with the understanding of the problem.

I decided to look for information regarding the growth of cyanobacteria and have found a number of papers regarding it. Unfortunately, I can only get the abstracts for a number of the papers so cannot look at the discussions, conclusions, methodology etc. There actually is a fair amount of research on cyanobacteria, mostly as it relates to blooms and water supplies. Some of the papers might be of interest to other members.

https://www.tandfonline.com/doi/pdf/10.5268/IW-6.2.938?needAccess=true

"Combined effects of nitrogen to phosphorus and nitrate to ammonia ratios on cyanobacterial metabolite concentrations in eutrophic Midwestern USA reservoirs"

This paper suggests the following:

• Species of Cyanobacteria can have different growth characteristics based on the species. There are a number of different species. This is not the major emphasis on the paper.
• TN:TP ratio (Total Nitrogen to Total Phosphorus) is important, a low ratio, ie relatively more phosphate in relation to nitrogen, is more encouraging to cyanobacteria growth.
• NO2:NH3 ratio is of higher importance in this paper. The lower the ratio the more favorable to cyanobacteria

Benthic freshwater cyanobacteria as indicators of anthropogenic pressures

Freshwater cyanobacteria are hardly used as biological indicators of anthropogenic pressures, possibly for two main reasons: (a) their response to ant…

www.sciencedirect.com

"Benthic freshwater cyanobacteria as indicators of anthropogenic pressures"

This paper looked interesting but I couldn't read it without paying a fair bit for the privilege

• "Orthophosphate was more influential for community composition than nitrate" - this is assumed to mean that the phosphate encourages cyanobacteria based on other document trends.

Cyanobacteria abundance and its relationship to water quality in the Mid-Cross River floodplain, Nigeria

"Cyanobacteria abundance and its relationship to water quality in the Mid-Cross River floodplain, Nigeria"

This paper looked at the nutrient regime and the species of cyanobacteria.

• "Several studies revealed that cyanobacteria are generally poor competitors for phosphorous in comparison to diatoms and green algae (Sterner 1994, Fujimoto et al. 1997). This is probably why they rarely dominate oligotrophic waters (Downing et al. 2001)" - If phosphates are lower then the eukaryotic plants can outcompete the cyanobacteria.
• Cyanobacteria is encouraged when algae is consumed by the plankton
• This paper in the discussion mentions a low N ratio helping to limit the cyanobacteria. I found this confusing because previously in the paper it suggested the opposite. In the statement they mention both are high, maybe neither is limiting. Contradicts previous paper.

https://journals.asm.org/doi/full/10.1128/AEM.71.6.3379-3383.2005

"Nitrate and Phosphate Affect Cultivability of Cyanobacteria from Environments with Low Nutrient Levels"

Not very useful, focused on one type of cyanobacteria which I don't believe is common in aquariums.

Specific responses to nitrogen and phosphorus enrichment in cyanobacteria: Factors influencing changes in species dominance along eutrophic gradients

Anthropogenic eutrophication is a worldwide problem, causing proliferation of cyanobacterial masses, some of which may be toxic. However, little is kn…

www.sciencedirect.com

"Specific responses to nitrogen and phosphorus enrichment in cyanobacteria: Factors influencing changes in species dominance along eutrophic gradients"

This paper looked like it would have some good information but I can only see snippets:

• Each Cyanobacteria species has does best in different nutrient regimes. This might be more significant than the TN:TP ratio.

I would be very interested if anyone else has looked at the growth of cyanobacteria for possible solutions to a common problem many of us have.

How I thinking about cyanobacteria after my websearch.

• Eukaryotic plants typically are better at using phosphates than cyanobacteria
• Cyanobacteria is better than eukaryotic plants in using nitrogen compounds in particular NH3
• When the nitrate levels are low but the phosphates high the cyanobacteria metabolize the ammonia before the plants can get to it, plants become nitrogen limited and thus cannot metabolize as much NH3
• When the phosphate levels are low the eukaryotic plants outcompete, the cyanobacteria making more NH3 and NO3 available to the plants.

This would suggest to limit the cyanobacteria we need to focus more on treatments and activities that will reduce the phosphates, but at the same time not being too aggressive in limiting the NO3. The addition of NO3 might have a short term effect of decreasing the cyanobacteria if the phosphates are also nearly limiting. Low NO3 in conjunction with high Phosphate encourages cyanobacteria as does having both high. If you lower the NO3 you also have to lower the Phosphate.

 

[DoubleDutch]

Most of us that have raised fish at one time or another have run into an issue with cyanobacteria, myself included. Frequently a number of people suggest that we are out of balance or that we have too large of a nutrient load in our aquariums. Conversely there is some anecdotal statements that the cyanobacteria growth is encouraged with decrease nitrate in the water with some on the reef and planted aquarium sites suggesting adding NO3 to the tank to help. These statements are often not helpful because they really don't help with the understanding of the problem.

I decided to look for information regarding the growth of cyanobacteria and have found a number of papers regarding it. Unfortunately, I can only get the abstracts for a number of the papers so cannot look at the discussions, conclusions, methodology etc. There actually is a fair amount of research on cyanobacteria, mostly as it relates to blooms and water supplies. Some of the papers might be of interest to other members.

https://www.tandfonline.com/doi/pdf/10.5268/IW-6.2.938?needAccess=true

"Combined effects of nitrogen to phosphorus and nitrate to ammonia ratios on cyanobacterial metabolite concentrations in eutrophic Midwestern USA reservoirs"

This paper suggests the following:

• Species of Cyanobacteria can have different growth characteristics based on the species. There are a number of different species. This is not the major emphasis on the paper.
• TN:TP ratio (Total Nitrogen to Total Phosphorus) is important, a low ratio, ie relatively more phosphate in relation to nitrogen, is more encouraging to cyanobacteria growth.
• NO2:NH3 ratio is of higher importance in this paper. The lower the ratio the more favorable to cyanobacteria

Benthic freshwater cyanobacteria as indicators of anthropogenic pressures

Freshwater cyanobacteria are hardly used as biological indicators of anthropogenic pressures, possibly for two main reasons: (a) their response to ant…

www.sciencedirect.com

"Benthic freshwater cyanobacteria as indicators of anthropogenic pressures"

This paper looked interesting but I couldn't read it without paying a fair bit for the privilege

• "Orthophosphate was more influential for community composition than nitrate" - this is assumed to mean that the phosphate encourages cyanobacteria based on other document trends.

Cyanobacteria abundance and its relationship to water quality in the Mid-Cross River floodplain, Nigeria

"Cyanobacteria abundance and its relationship to water quality in the Mid-Cross River floodplain, Nigeria"

This paper looked at the nutrient regime and the species of cyanobacteria.

• "Several studies revealed that cyanobacteria are generally poor competitors for phosphorous in comparison to diatoms and green algae (Sterner 1994, Fujimoto et al. 1997). This is probably why they rarely dominate oligotrophic waters (Downing et al. 2001)" - If phosphates are lower then the eukaryotic plants can outcompete the cyanobacteria.
• Cyanobacteria is encouraged when algae is consumed by the plankton
• This paper in the discussion mentions a low N ratio helping to limit the cyanobacteria. I found this confusing because previously in the paper it suggested the opposite. In the statement they mention both are high, maybe neither is limiting. Contradicts previous paper.

https://journals.asm.org/doi/full/10.1128/AEM.71.6.3379-3383.2005

"Nitrate and Phosphate Affect Cultivability of Cyanobacteria from Environments with Low Nutrient Levels"

Not very useful, focused on one type of cyanobacteria which I don't believe is common in aquariums.

Specific responses to nitrogen and phosphorus enrichment in cyanobacteria: Factors influencing changes in species dominance along eutrophic gradients

Anthropogenic eutrophication is a worldwide problem, causing proliferation of cyanobacterial masses, some of which may be toxic. However, little is kn…

www.sciencedirect.com

"Specific responses to nitrogen and phosphorus enrichment in cyanobacteria: Factors influencing changes in species dominance along eutrophic gradients"

This paper looked like it would have some good information but I can only see snippets:

• Each Cyanobacteria species has does best in different nutrient regimes. This might be more significant than the TN:TP ratio.

I would be very interested if anyone else has looked at the growth of cyanobacteria for possible solutions to a common problem many of us have.

How I thinking about cyanobacteria after my websearch.

• Eukaryotic plants typically are better at using phosphates than cyanobacteria
• Cyanobacteria is better than eukaryotic plants in using nitrogen compounds in particular NH3
• When the nitrate levels are low but the phosphates high the cyanobacteria metabolize the ammonia before the plants can get to it, plants become nitrogen limited and thus cannot metabolize as much NH3
• When the phosphate levels are low the eukaryotic plants outcompete, the cyanobacteria making more NH3 and NO3 available to the plants.

This would suggest to limit the cyanobacteria we need to focus more on treatments and activities that will reduce the phosphates, but at the same time not being too aggressive in limiting the NO3. The addition of NO3 might have a short term effect of decreasing the cyanobacteria if the phosphates are also nearly limiting. Low NO3 in conjunction with high Phosphate encourages cyanobacteria as does having both high. If you lower the NO3 you also have to lower the Phosphate.

Aren't you "simply" saying it is an unbalance? Would be completely logical to me if one realises Cyaono often occures in new set ups (for a while). Also iften it is a combination with bad plantgrowth (which might have the same cause). Why exactly has one to lower PO4 if one lowers NO3 ? Doesn't that depend on the levels tested?

 

[GaryE]

So we come to the obvious we always overlook. There is more than one living thing we can call Cyanobacteria, and there is more than one set of conditions that favour growth. My Cyano advice may not apply to your Cyano.

Ah, that biodiversity...

 

[Uberhoust]

Why exactly has one to lower PO4 if one lowers NO3 ? Doesn't that depend on the levels tested?

The point is that you want the limiting factor to be the factor that the "normal" plants are more effective at utilizing. This creates a deficiency for the cyanobacteria, allowing it to be out competed. Yes, it would depend on the levels tested. If you make the limiting factor the nitrogen compounds, then you risk the cyanobacteria being dominant. If the limiting factor is the phosphate perhaps the plants have a better chance.

Quite honestly for me I find cyanobacteria to be more of an issue after the tank has been setup for a while. I was hoping that some other members would provide other research avenues. The Nitrogen Phosphorus balance gives something to target during treatment, it might not be correctly, and doubtful it is the only factor. It is also a problematic because most people in freshwater do not know their phosphate levels.

 

[WhistlingBadger]

My 150g, set up for a year and a half, has been having a pretty bad CB outbreak for several months. Nitrates consistently measure less than 5 ppm, and phosphates don't register at all. I've reduced the photoperiod and increased water circulation at the lower level. Perhaps I need more nitrates? That seems counterintuitive, doesn't it?

 

[Uberhoust]

My 150g, set up for a year and a half, has been having a pretty bad CB outbreak for several months. Nitrates consistently measure less than 5 ppm, and phosphates don't register at all. I've reduced the photoperiod and increased water circulation at the lower level. Perhaps I need more nitrates? That seems counterintuitive, doesn't it?

It's this type of comment that suggests to me we really don't know what we are dealing with, I am in a similar boat. If I interpret what I have read the cyanobacteria are very efficient in capturing the NH3, more so than our plants, so if you don't get any nitrates, you know that the ammonia has to be going somewhere. The literature suggests that it is going to the cyanobacteria, almost like it is taking the role of the nitrifying bacteria. In the studies that looked at just the metabolites of cyanobacteria the ammonia and nitrate and phosphate might not register on our simple test kits.

In your case it would appear that you are limited on both N and P, this is a case I haven't read about. The more cyanobacteria the more difficult it is to remove.

I want to be clear, my hope is we get some discussion on this. I don't think what I have read so far is the answer and some if it is contradictory as well there are a lot of other variables. I am off to get my phosphate test kit this afternoon. My 75 gallon tank now is pretty bad, I kind of gave up on it, so I will use it as a bit of a testbed. My 37 next to it is doing well, with heavier stocking. The only differences are the lighting and the substrate. I will post any findings and would encourage anyone to post their findings.

 

[Uberhoust]

No phosphate tests in Nanaimo.

 

[Uberhoust]

So been thinking on this for a bit. Possibly one issue we have is how we measure nutrients in an aquarium. In general high nitrates is often considered an indicator for general nutrient load in the tank. Is there something better.

I also found a PO4 test kit and ran a full round of tests on my aquarium with the cyanobacteria, CB.
(previous water change was 2 weeks prior to testing, I haven't been keeping up with this tank)

pH = 7.2 (higher than my other tank, substrate issue?)
NH3 = 0.0
NO2 = 0.0
NO3 = <5.0 (just slightly below the color mark) (approximate 2.5ppm after the water change, only value that changed)
PO4 = 0.0 (might have just a tad of color but v. low)
KH = 40 ppm (this suggests carbonates in the substrate that were missed)
GH = 0 ppm (expect it is closer to 5 ppm, this was expected)

If NO3 and PO4 are indicators of nutrient load in the tank then my tank would have very low nutrients. This kind of makes sense because I don't feed heavily, nor every day, and in the 75 gallon where the CB is an issue has only 2 adult angels, 4 juvenile angels, and 3 small tetras. Filtration is with a Fluvial 407 with all trays filled with biological substrate, water pulled from one side of the tank and re-introduced on the opposite side.

After testing I cleaned and performed a water change on the tank. I cleaned off all removable CB off the plant leaves, and substrate, as well as the windows. I pulled 60% of the water from the tank and replaced it, was going to be more but my angels were breeding again and I didn't want all their eggs gone, makes them upset. During the cleaning I noticed that the vegetation was a bit yellow even those that did not have any CB growing on them. I looked that the nutrient deficiencies on the Aquasabi site https://www.aquasabi.com/aquascapin...oms of a phosphorus,an increase in spot algae. It would seem that because the newer leaves are a better green than the older that I have a nitrogen deficiency. Though I am also suspecting that I have other deficiencies as well.

In any case I removed all of the dead or dying plant material, added 10 Seachem fertilizers tabs to the substrate. I am going to leave it at that to see what happens. After the water change the nitrates are now closer to 2.5 ppm. This morning the CB has migrated back to the surface of the substrate (sand in this case). I have some liquid fertilizer but waiting to see what the tabs do first.

Before (note new eggs on stump, the two angels in the front are always breeding, the other two are their children, I didn't see these at first)
The amazon swords are juveniles I got from one that flowered a year ago, not going to happen in this tank.

After the cleaning, adding more wood, trimmed jungle val. Half the eggs dried out, all were exposed at some point but only the top half all died.

Gratuitous picture of 7' jungle val leaves when cleaning the small tank next to the problem tank. On one of my home built but unfinished aquarium stands.

 

[OnlyGenusCaps]

This would suggest to limit the cyanobacteria we need to focus more on treatments and activities that will reduce the phosphates, but at the same time not being too aggressive in limiting the NO3.

This is an interesting topic, thanks for starting it! I have had a look through the full papers you cited (and a huge thanks for doing that!!!) and I think you have the correct take away here. As a general understanding about cyanobacteria (at least the types most likely to inhabit aquaria), many are capable of fixing nitrogen. This means they can essentially operate independently of the nitrogen availability to the plants. Indeed several of the species listed in your papers are known facultatitve nitrogen fixers - see Nostoc as an example.

Knowing this I am not surprised that P played a large roll in the types and density of cyano present in these systems. And likewise it would not be shocking to me if it will play a role in its prevalence in our tanks. One thing to remember though is that once a population of algae of any sort has established, you might not see high levels in the tank as the biomass now contains the previously high levels, and the population has grown to the level where uptake is matching inputs. I have found that in some cases, I am able to predict an algal outbreak by regular testing. I'll see the spike in the testing a week to a month before algae visually begins to "take over". There was a perturbation in the system, and the result is a shift in the balance of the of the populations and densities of the species (yes, a tank loaded with algae is "balanced", just not the way the owner may want it to be - indeed the whole concept of "balance" as used in the aquarium hobby I think holds our understanding of these systems back, it should be stricken from the vernacular).

To prevent cyano, it does seem reasonable to limit P. I suspect that's correct under most circumstanceds. But once you have an outbreak, trying to shift back to, what is termed an "alternate, stable state", where the plants dominate and all the algae is repressed I would expect to be a different challenge. I can illustrate this by thinking of a drought. Even a severe one. A drought alone is unlikely to change the forest at the edge of a prairie into the alternate state of being a prairie, with more dry tolerant grasses. The trees are well established, and resistant to this perturbation. Once the rains come again, it will still be a forest, if a slightly weakened one. A fire might, unless it is followed by no fires, and then the available tree seeds will over take the prairie grass again. So while limiting P might prevent cyano from blooming in a tank, it might not be the solution to get rid of the already spread cyano. Does that make sense? I'm not sure how well I am doing with my explanations here.

Regardless, I believe you are on the right path to really understanding the micro-environments that we create in our aquariums with this sort of inquiry. This approach, parsing through what is known, and trying to find solutions that are generalizable, is the sort of thing that advances our understanding of the hobby! Not hand waving broad statements about "balance", which may as well be your tank's horoscope.

 

[raylove]

My cyanobacteria problem is modest yet persistent. My nitrates are low at 5ppm but my tap water averages about 30ppm so the level rises temporarily after a water change - the CB gets a little worse until levels fall again. It's almost like it is the fluctuation that causes the issue rather than the actual level of nitrate itself. This seemed to be upheld when I experimented and did no water changes for three weeks - the CB did get a lot better but returned to 'normal levels' when I started again. The bigger the water change the worse the CB gets, but of course the larger the water change the larger the fluctuation too!
I also have zero phosphate so I now dose phosphate to encourage better plant growth as I hoped that might help. Plants certainly showed accelerated growth and greener leaves but no real change to the CB - maybe a little better.
As I say, my issue is modest so I can live with it but it won't stop me trying to eliminate it.

 

[GaryE]

It is a good thread and one I am reading carefully.

I have a rack with 24 10 gallon tanks on it, end out. All have the same basic air filtration, pool sand substrate from the same source and shared overhead light strips. Each has 2 acrylic mops, and a pair of killies. I change 30% of the water every 7 to 10 days.
One tank in the row, on the lower level, has had terrible cyano outbreaks. It's on its 3rd blackout in 7 months right now. None of the other tanks show any cyano, and all not only look but smell clear.
Some of the tanks in the top row have Elodea and terrestrial plants roots in, but the lower rack 12 are all the same. Except one.

It's a complex creature, that Cyano...

 

[Uberhoust]

@OnlyGenusCaps, pretty good summary. You mention the alternate state, and that is something I have considered but yet don't know how to quantify or qualify, I used to work in forestry and you can see what you describe in various forest lands. In regards to a tank the process to prevent cyanobacteria could, and likely is different than a process to remove it.

The 75 gallon tank in the pictures above has had a cyanobacteria problem for probably a year, never really bad, but never good either. Frequent removal of the growth will reduce the population, but it is always there.

I use Nitrates and Phosphate concentrations of an indication of the nutrient load in the tank but in another thread the Total Dissolved Solids is also a metric that could be used.

Last weekend I did a number of samples and a 60% water change, adding NilocG fertilizer to the tank to see what would be the affect of additional nutrients.

2022.12.18
Pre Water Change - NO3 5 ppm, PO4 0 ppm, Cyanobacteria 20% gravel surface with <5% on glass in low current area
Post Water Change - NO3 2.5 est, PO4 0 ppm, Cyanobacteria <5% sand (most discarded with water change) 0% on glass, removed from all plants
Post Fertilizer - NO3 7.5 est, PO4 0.25 ppm, Amazon Swords doing poorly but the Jungle Val and the normal Vals are actively growing.

2022.12.21
No tests on water but the cyanobacteria is about 15% coverage over the sand, with none on the glass. Fish are fine. Most cyanobacteria is only a light trace with an accumulation in a plant clear area of the sand.

So now the Nitrates are higher than normal, this is why I initially stopped using this fertilizer, I am hoping the phosphate level is still restrictive but I was thinking the that overall nutrient availability was too low to make the plants grow vigorously.

@GaryE and @raylove, it is good to hear you are having similar issue but also work to keep your tanks to what we believe to be healthy. I am going to order a probe for the TDS (I assume it is more a measure of conductivity) and add it to list of items I track. Perhaps if we started monitoring our tanks, getting more people to do so, and sharing the results we might be able to find some correlation, it would be difficult to do with only one sample site. It would also be good if we had a simpler way of determining the species, right now I am 50% guessing that I have Oscillatoria sp. based on it being a simple filament that has definite motion you can watch in the microscope.

 

[OnlyGenusCaps]

I used to work in forestry

Ah, so you are well familiar with the concept of alternate stable states! I hope my explanation didn't inadvertently make you feel as though I was talking down to you. If so, I apologize. Please know, that is never my intent toward anyone, ever.

I was thinking the that overall nutrient availability was too low to make the plants grow vigorously

I've run into this issue more often than not, and for me it has been strongly associated with favoring certain types of algal growth. And a frustration.

right now I am 50% guessing that I have Oscillatoria sp. based on it being a simple filament that has definite motion you can watch in the microscope.

That sounds highly likelihood to me from your description. And it would account for its presence in one tank but not others as that genus spreads primarily from fragmentation rather than spores, if my memory serves.

One tank in the row, on the lower level, has had terrible cyano outbreaks. It's on its 3rd blackout in 7 months right now. None of the other tanks show any cyano

Indeed @GaryE , you may also have a fragment spreading type if you only have it in one tank. This is true for me as well. I have a tank with cyano, that I believe came in on petrified wood I did not bother to sterilize, and it doesn't infect any other tanks. This is also true of BBA, staghorn algae, and several hair algae lineages as well. They do not spontaneously appear; your tanks essentially get inoculated with them. This is why I caution those with multiple tanks to use hygienic techniques when sharing equipment between them.

I assume it is more a measure of conductivity

Spot on! TDS meters are actually EC (electrical conductivity) meters. The "ppm" is a calculated value, and can vary depending on the exact equation the manufacture uses. ∴ if you want comparable values between different meters, use the EC measurement units.

 

[Uberhoust]

Still on the cyanobacteria.

Dec 27 2022 (60% Change)

• Before 10ppm Nitrate 0.25 ppm Phosphate reasonable amounts of Cyanobacteria less than last time.
• After water change <5 ppm Nitrate <0.25 Phosphate
• Added dose of NilocG Thrive 5-10 ppm Nitrate 0.25 phosphate

Jan 2 2023 (80% change - note my water chemistry is almost identical to tank chemistry in regards to pH GH and KH, complete filter clean, except the hoses )

• Before water change 10ppm Nitrate, 0.25 phosphate. Cyanobacteria is definitely worse with the NilocG Thrive, we will be discontinuing its use. All plant growth improved but cyanobacteria is starting to affect the plants again.
• After, <5 ppm Nitrate, <0.25 phosphate, both show trace amounts only.

For this week I am not fertilizing with a liquid fertilizer, the first application after a large water change didn't seem to influence the cyanobacteria much, but the second application made things much worse. The affect on the cyanobacteria is unfortunate because the plants seemed to have really picked up with the liquid fertilizer, suggesting I have a deficiency with some nutrient. During the cleaning I try to remove as much cyanobacteria as possible. The main location of cyanobacteria is the substrate with some starting on the leaves and glass.

I am setting up a 60 gallon so that I have a home for the fish and plants, I am then going to tear down the 75 and change the substrate to something similar to my other tank that doesn't seem to get cyanobacteria (TBH it has had the bacteria but it went away and stayed away since I moved away from aquarium soil). In the meantime the cyanobacteria is not affecting my angels, unless it acts like an aphrodisiac, they are getting ready to breed again, so I will continue to try and find some strong reason why I have issues with cyanobacteria in the tank. I am also looking for liquid ferts that do not up my nitrates.