What exactly is fluctuating CO2 in relation to BBA

[Nikhedonia]

Hi...new to posting on this forum but have been reading as a guest for several years.
I've joined to ask a question that may seem stupid but I can't find a thread that answers it.
I'm not going to talk initially about lighting levels, fertilisation regimes, flow rates, substrates etc...If helping you understand my problem requires that information I will provide it. I will also give feedback on the new setup I'm going to attempt and let you know about the results of any insights that you can or are willing to provide.
Here it is
If a particular planted tank requires 50 arbitary units of CO2 per day to flourish and one day I give it 45 and the next 55...which is worse.
I assumed that going below is worse...but I've started to wonder based on very bad experiences with BBA if above could also be the problem.
In other words if I'm too often below then the plants starve and that must be bad...If i'm too far above then I assume that just like for fish etc the levels will become toxic also for plants.
But does it matter if my levels are adequate i.e 50 but not toxic perhaps 56.
Do I always have to hit 50 exactly or can I do anything from 50 to 55.
If plotted on a graph my CO2 levels must be exactly 50 everytime or perhaps 51 everytime or whatever...then I probably can't do that with my setup and will have to try something else.
If I have a little wriggle room then maybe I can. ie one day 50 another 53 another 52 etc
So back to the question....what exactly is fluctuating CO2
I know I havent provided enough info for a detailed analysis but in general how precise must CO2 injection be.

Best regards

 

[hypnogogia]

AFAIK fluctuating CO2 is when the CO2 concentration doesn’t remains steady during the photo period. The idea is to turn on CO2 before photo period begins to increase ppm of CO2 in the water to desired level and then to keep it there while the lights are on. I.e. rate of CO2 consumption plus loss at water surface = rate of introduction to water.

 

[Ria95]

It’s not a bad question, doubt you will find an evidence based answer regarding CO2 fluctuation and BBA growth. You will often hear people talk about feel good concepts like equilibrium, stability and balance . The concepts are nice, and you will get a spoon full of theories, when it comes to measurable parameters and thresholds things start to be quiet. Some people start to get concerned at a pH difference of 0.1 during the light period from their target, based on the accuracy of common equipment it‘s not a bad point, but may or may not have anything to do with BBA growth.

If a particular planted tank requires 50 arbitary units of CO2 per day to flourish and one day I give it 45 and the next 55...which is worse.
I assumed that going below is worse...but I've started to wonder based on very bad experiences with BBA if above could also be the problem.
In other words if I'm too often below then the plants starve and that must be bad...If i'm too far above then I assume that just like for fish etc the levels will become toxic also for plants.
But does it matter if my levels are adequate i.e 50 but not toxic perhaps 56.
Do I always have to hit 50 exactly or can I do anything from 50 to 55.

Doubt we can talk about CO2 toxicity in plants in an aquarium with fish. If memory serves, for maize symptoms of CO2 toxicity were reported at 10 000ppm CO2 in air. Let me complicate your model a little (in too much detail, if so please ignore)... in order for the plant to profit from those 50 required units of CO2 during the light period, the plants needs access to it at all time points. In other words, the daily sum of 50 units CO2 works great when it means that 5 units of CO2 are available for each of 10 hours of the light period, or 0,0014 units of CO2 are there for every second of that light period. And that is only for the required CO2.
Complicate it further, how do we make sure those 0.0014 units that they require actually get to each plant? Speaking figuratively, plants can‘t go look out for their food, so the food needs to be in abundance (high concentration) near them. We increase the flow around the plants but also increase the concentration so that for every point in time enough is present for one plant to take what it needs and the next one downstream will still have enough. Actually achieving ’stable CO2’ levels at plant level is more challenging than it seems.

The best explanation/theory I have seen, between fluctuating CO2 levels and BBA is that plant’s tissue gets damaged/is discarded by the plant when CO2 fluctuates(drops below a required level), more organics get released in the water column encouraging BBA. Thus in theory, if the plants are in proper health it should not matter (then again, see the beginning of my post).

 

[_Maq_]

I'm sceptic of that whole 'unstable level of CO2' thing. In nature, nothing like that exists. If plants were to react strongly negatively to CO2 fluctuations, they could not survive in nature.
On the other hand, I agree that any fluctuation (light, temperature, O2, CO2, nutrients, pH, ...) in conditions in our tiny tanks is a matter of concern. I tend to believe that the crucial event is the change in activity of the microbial community.

 

[zozo]

I'm sceptic of that whole 'unstable level of CO2' thing. In nature, nothing like that exists.

That is true, with the natural equilibrium it's not uncommon to measure a Ph 7 in the morning and a Ph 8,5 in the late afternoon and it's the natural CO² content and plant metabolism during the day doing this. And the only setup where I have never encountered any BBA and that in my outdoor garden setup.

It also can't exist in a High Tech Aquarium I guess what truly is meant is "Relative stability".

If you would use a drop checker then all there is, is a colour that takes about 2 hours to react to change colour and it does this extremely gradually. From this standpoint, stability can't be accurately determined and it could fluctuate In quite some range without notice.

In general, is explained, plant metabolism doesn't skyrocket the moment to lights switch on but the plant CO² uptake gradually increases and takes a few hours to reach a maximum uptake. Thus if you would have a stable CO² input x bubbles p/m then the Ph still should rise and you should measure different Ph values during the length of the light cycle. This actually says with a stable Ph during the light cycle with the use of a Ph controller only can mean a waste of CO² pumping in more than it needs. This would also count for manual Ph measurement and chasing the constant 1Ph drop during the entire light cycle.

Can stability this way really be determined and put into numbers within a dynamic uptake-changing environment? What is it and how does it relate to the other factors?

 

[Wookii]

I'm sceptic of that whole 'unstable level of CO2' thing. In nature, nothing like that exists.

Very true, but in nature algae proliferates also - and that's the thing we often try to minimise in the aquarium.

 

[_Maq_]

but in nature algae proliferates also

Much has been written in scientific papers about two contrasting states of natural waters: (1) clear water, where macrophytes prevail and suppress algae, and (2) green water, where cyanobacteria and algae are the winners and macrophytes largely disappear. But the mechanisms causing turn from one to another are not completely understood. In general, eutrophication leads to the latter.
Yet as we know, in our tanks, algae proliferation poorly correlates with amount of nutrients. Hobbyists practicing Estimative Index should struggle with algae invasions, but - as a rule - they don't. And "lean" tanks are not protected from cyanos and algae either.
Like I said, I quite believe in changes in conditions as a trigger, and I believe microbes are the prime drivers. I take algae for mixotrophic, and I believe minimizing the amount of dissolved organics is the good way to go. Apparently, measures like activated carbon filtration sometimes work and other times don't, but I think it's subject to microbial activity.

Right now, I'm running a test in my Michurins, to document Mg, Ca and K deficiency. I change half the water every week with NO addition of the nutrient in question, while all other nutrients keeping in full supply. I'm waiting for two months already, and NO visible signs of deficiency appeared. It's astonishing esp. in the case of potassium, which I always dose sparsely and it should be consumed within a short period.
How's that possible? Here is the only answer I can think of: The tanks were established in spring '22. Plain silica sand. I believe the substrate is now, over a year later, full of organics, both live and dead matter, and these serve as a reservoir of nutrients for the plants. In fact, I can recall that a year ago, in the very same tanks, various nutrient deficiencies were almost permanent.
If my assumption is correct, it has important implications. It may be an important part of what we know as an "old, stabilized aquarium". Also, it seems to contradict the fears of "nutrient depletion of substrate", "nutrient deficiency of silica sand", and the necessity to establish tanks with substrates rich in nutrients. (It all conforms to my belief; I don't like the business of selling nutrient rich substrates.)

 

[LondonDragon]

I don't like the business of selling nutrient rich substrates

I don't think that matters much either, might help for a short period but in the long run you are better off with gravel/sand! Also easier to maintain long term without turning your aquarium into a mess! I have tanks running with sand/gravel for 10 years and no issues, no dosing and plants do just fine and no algae in sight either, no glass cleans!

 

[xZaiox]

I've started to wonder based on very bad experiences with BBA

I know your topic is specifically about BBA and CO2, but I just wanted to throw in another curveball - I had persistent issues with BBA for over a year, and I followed all the CO2 guides to the letter with no results. I even upgraded my CO2 regulator's needle valve so that I could get veeeery stable CO2. The BBA wasn't phased whatsoever. It was only after speaking to @Happi that I was advised to reduce iron dosing, and this actually worked. I had been dosing anywhere between 0.5 - 1 ppm Fe in various forms (EDTA, DTPA, EDDHA, Gluconate). I now dose 0.15ppm EDDHSA and 0.05ppm Gluconate weekly, and my BBA is 99% gone.

I'm not saying the "one and only" cause is iron related, but reducing iron is what got rid of it in my tank. Messing with the CO2 had no effect for me. Perhaps my CO2 was already stable enough beforehand? I don't know... Iron did the trick.

 

[Nikhedonia]

Hi thanks for the replies....all appreciated.
I started this tank about seven years ago. Low tech soil and sand with citrate and bicarb CO2, moderate lighting all on timers. Worked great for about five years....good flow rates and moderate ferts, CBM+ and phosphate and potassium. Plenty of nitrate in my tap water plus the extra I get from my fluidised sand filter.
Heavily planted.
Everything grew really well...then after about five years because of family issues and work concerns a period of neglect.

BBA.

I've tried everything I can Google...I can't get rid of it.
I thought finally there might be a difference between accuracy and precision as far as CO2 and BBA is concerned.
Starting to come to the conclusion that I don't care.
If I could manage it a little better, then the one thing I know is I can grow BBA really well...everything from nearly white to slate grey...black down to deep maroon...Short little tuffs to deep waving beds.
It looks really good...if it wasn't so invasive I don't think I'd care.

Best regards

 

[Andy Pierce]

My experience was that once BBA has taken over, treatments don't work and nothing short of a full-tank reset will shift it. I think (my opinion) the biggest driver of BBA is organic waste from insufficient water change maintenance, either because large and frequent enough water changes are not happening, or because debris is trapped e.g. in areas of inaccessible hardscape such that water changes and/or other methods don't dislodge it. This seems consistent with your "period of neglect" you've described. The good news is that since for five years you didn't have a problem, if you go back to what you were doing before, BBA won't come back. Maybe after five years, you're ready for a reset to try some new concepts anyway?

 

[_Maq_]

I think (my opinion) the biggest driver of BBA is organic waste

That.
Perhaps filtration using activated carbon and/or Purigen would be worth trying. And regular WC, of course.

 

[LondonDragon]

regular WC, of course

This is the key! and keep your stock levels in check. I find that most people don't clean their filters often, in my high-tech I need to clean the filter at least once a month, or I get BBA, and "hoover" the substrate with a gravel cleaner! on my long established low techs, I clean the filter once every 3 months or so.

 

[xZaiox]

I've tried everything I can Google...I can't get rid of it.

Can I ask how much iron you're dosing?

My experience was that once BBA has taken over, treatments don't work and nothing short of a full-tank reset will shift it.

For what it's worth, mine had completely taken over too. It was smothering my carpet plant, all over the anubias and bucephelandras, the java ferns, it grew on the lower growth of all my stems and slowly worked its way up. Simply reducing iron outright killed it off for me, I didn't even have to cut the old anubias/bucephelandra leaves off, it gradually retreated on its own. I did cut and replant the tops off the stems though.

I think (my opinion) the biggest driver of BBA is organic waste from insufficient water change maintenance, either because large and frequent enough water changes are not happening, or because debris is trapped e.g. in areas of inaccessible hardscape such that water changes and/or other methods don't dislodge it.

When my tank had massive blooms of the stuff, I was doing regular 50-60%+ water changes and cleaning the filter every 1-2 weeks. I now change 40% per week and clean the filter usually between 6-8 weeks. I do think that organic pollution seems to drive it/make it worse, but I do find it interesting that my maintenance has decreased quite a lot now, and yet my tank is mostly free of BBA from just reducing iron. I also have a high stocking of fish that eat a lot.

I can only go by own experience with the menace. I appreciate there may be multiple causes of it. If anyone is experiencing persistent BBA and dosing a high amount of iron though, I definitely think it's worth trying a simple reduction before redoing a whole tank, that's a lot of work

 

[eminor]

I had BBA bloom when I introduced driftwood, BBA is still there, it doesn't bother me as much as before but still one of the ugliest algae I've ever seen. I don't know if organic is related to nitrates but that tank was running with indetectable nitrate, BBA still was there. Maybe the driftwood still deliver some organic matter that i can't see ? that driftwood has been in a pond for some times and was let dry for a long time after. When i cleaned it there was no tannins, water was clear

Co2 is perfect, even the lowest stem leaves are pearling, i have more BBA in the outlet path, that algae definitely love flow. I already had BBA but this time i don't see how I can beat it, it's not a crazy bloom either. Even H2O2 does nothing to it. Fast-growing plants don't have it or really low amount that i can't see. I highly doubt that algae is CO2 related, in the 5 past year I've been struggling with CO2, even my lowest leaves in the dark is still there for months.

Could be the bioload too, 13 tetra cardinalis, 4 corydoras, 1 bristlenose pleco in a 26 gallons with a big tetra 1200ex plus canister filter

 

[bazz]

i have more BBA in the outlet path, that algae definitely love flow

I totally agree with this with a tuft forming on the inside of my lily pipe when I've not cleaned it for a while, but I also occasionally find a tuft under a Buce close to the substrate where there is probably less flow and more organic waste.

 

[tigertim]

I find that most people don't clean their filters often,

That would be me, a once a year clean every spring.
I agree though i think BBA is organic waste related though, i also found Amano shrimps helped get it under control when i had a outbreak a year ago that covered all the wood in the tank, of course small water changes help twice a week.

 

[Simmo]

In my low tech definite correlation with organic content of the tank; most severe event was after a period of neglect ,current localised BBA is on old aquarium wood only, I know the wood is friable to an extent even though it does not colour the water, regular wire brushing of the BBA and organic mulm from the wood is effective.

 

[Oldguy]

For my two cents worth. BBA can tolerate low light and low dissolved CO2, taking CO2 from hydrogen carbonates and appears like high organics.
I had a slow but growing BBA presence and removed ALL bogwood, which had become very soft. The amount of mulm in the substrate was disconcerting.
I now have a wood free tank and BBA has all but gone but like herpes simplex it may always be lurking waiting for the tide to turn in it favour.
The reduction in iron may result in increased availability of phosphate, its a sod that nothing is simple.
BBA appears to becoming common in LFS on slow growing plants, I believe there are several species of this menace.

 

[Andy Pierce]

I have similarly found a disconcerting amount of mulm hiding in the root structures of epiphytes growing on hardscape. I am quite aggressively going "turkey baster water blaster" on it to try to bring the levels down.