• You are viewing the forum as a Guest, please login (you can use your Facebook, Twitter, Google or Microsoft account to login) or register using this link: Log in or Sign Up

What exactly causes BBA? Part 2 - Bacterial imbalance

The lowered O2 levels is to be expected, but how much lower and does this actually contribute to algae growth?

If aerating at night, wouldn't that actually lower O2 levels because it's speeding up equilibrium?
 
Last edited by a moderator:
I forget the actual numbers and times but essentially O2 levels in ponds peak about 2 in the afternoon. I think the whole point of night time aeration is simply to prevent the co2 levels from getting too high.
 
But it's not the O2 that directly stops algae; it's the increase in bacteria, archaea, and other microbes.
 
According to this theory ... a reduction in CO2 reduces the O2 produced through photosynthesis and plant growth, which means that the heterotrophic and autotrophic bacteria must compete for oxygen.

When the oxygen levels reduce, the autotrophic bacteria are less able to compete and become dormant or die. Autotrophic bacteria convert CO2 as their carbon source, which requires a great deal more energy and oxygen than the heterotrophic bacteria to grow and reproduce (and function).

Heterotrophic bacteria use organic carbon molecules as their carbon source. As they consume organics, they break down proteins to release amino acids and ammonia. They also release phosphates, which photosynthesising plants and algae require (to create ATP in the Calvin cycle). Phosphates can be a limiting nutrient.

This means the nitrifying bacteria are converting less ammonia to nitrates, meaning an increase in ammonia concentration and less nitrates for the plants.

Industrial production processes have shown that a reducing oxygen concentration can increase the vitamin B12 production of certain Pseudomonas bacteria, a type of heterotrophic bacteria. A certain concentration of vitamin B12 and ammonia / urea are required by certain rhodophyta algae to produce compounds such as spermidine / spermine, which they need to reproduce.

Heterotrophic bacteria populations increase with an increasing C/N ratio. Driftwood has a high C/N ratio.

A reduction in gaseous CO2 means plants such as anubias may make greater use of dissolved bicarbonate ions as its carbon source. This leads to a concentration of OH- ions on the top surface of the leaf, which increases pH, attracts positive ions (e.g. Ca) and leads to a potential difference with the bottom of the leaf (which may mean that charged ions are drawn to the edge of the leaf). The increase in pH may go higher than the limit which the autotrophic bacteria can function at.

BruceF, concerning your comment concerning reducing CO2 reducing plant nutrient requirements and causing dieback is interesting. If reducing CO2 lead to the plants releasing organics before dying back, this would provide a food source for the heterotrophic bacteria.

ADA raise their lily pipes at night to increase oxygen. Oxygen output of photosynthesising plants greater than surface agitation (Henry's Law) will produce.
 
Guest said:
But it's not the O2 that directly stops algae; it's the increase in bacteria, archaea, and other microbes.
Click to expand...

It's the oxygen feeding the autotrophic bacteria (plus keeping organic carbon levels low), that stops the ammonia / B12 concentrations getting to the point that BBA can flourish.
 
Last edited by a moderator:
BruceF said:
I think the whole point of night time aeration is simply to prevent the co2 levels from getting too high.
Click to expand...

CO2 and O2 concentrations are independent of each other. True, more organisms will be respiring, taking in O2 and producing CO2 overnight, but CO2 levels will be less than injecting during the day. I think surface agitation at night stops O2 levels dropping too low, rather than CO2 levels getting too high.
 
AndyMcD said:
ADA raise their lily pipes at night to increase oxygen. Oxygen output of photosynthesising plants greater than surface agitation (Henry's Law) will produce.
Click to expand...

Andy, were you meaning that oxygen produced by photosynthesis is greater than oxygen produced by surface agitation?

Also, I was thinking: if more Co2 increases O2 production, increased Light must also increase O2 production... Which makes me think the opposite is also true: if Co2 decreases, less oxygen, if light decreases, less oxygen... Possibly then more plant matter dying for adapting to the new, lower light or lower co2 conditions, then more organic matter around, more heterotrophic bacteria, then possibly more BBA.

That's actually what happened to me a few months ago: I was tired to trim plants every week, so I reduced light and correspondingly Co2 a little to let plants grow less... Some plants begun to die, BBA appeared after 2-3 weeks or so.

Does this make sense to you guys?
 
fablau said:
Guest, what do you mean exactly? Isn't aeration increasing O2 anyway?
Click to expand...
The O2 concentrations during photoperiod will be much higher than equilibrium so surface agitation will outgas excess O2.

fablau said:
That's actually what happened to me a few months ago: I was tired to trim plants every week, so I reduced light and correspondingly Co2 a little to let plants grow less... Some plants begun to die, BBA appeared after 2-3 weeks or so.

Does this make sense to you guys?
Click to expand...

I found that reducing CO2 was what initiated a BBA outbreak over the course of a couple of weeks. I also got GDA.
 
Guest said:
The O2 concentrations during photoperiod will be much higher than equilibrium so surface agitation will outgas excess O2.
Click to expand...

Ok, what about agitating surface to increase O2 for fish that otherwise would suffer? I mean, how do you know if surface agitation is increasing O2 or it is decreasing it?
 
Last edited by a moderator:
fablau said:
Ok, what about agitating surface to increase O2 for fish that otherwise would suffer? I mean, how do you know if surface agitation is increasing O2 or it is decreasing it?
Click to expand...
Agitation only accelerates gaseous equilibrium.
If O2 is 10ppm, agitation will accelerate equilibrium down to 8ppm. O2 concentration drops faster.
If O2 is 6ppm, agitation will accelerate equilibrium to 8ppm. O2 concentration increases.

fablau said:
Exactly what I was saying, I agree with you. Did you happen to notice more dead matter around because of reduced Co2?
Click to expand...
No, but I didn't reduce light which caused plants to die.
 
Guest said:
If aerating at night, wouldn't that actually lower O2 levels because it's speeding up equilibrium?
Click to expand...

Immediately after the photoperiod it may reduce oxygen concentration to the equilibrium it can achieve through surface agitation alone more quickly.

However, overnight all organisms are consuming oxygen (plants, fish, algae, bacteria). Surface agitation means that you're keeping it at the lower level, better able to keep in equilibrium with atmosphere.

If you don't have surface agitation, the tank may be consuming oxygen with no generation until lights on.

Nitrifying bacteria would suffer.
 
Last edited by a moderator:
fablau said:
Also, I was thinking: if more Co2 increases O2 production, increased Light must also increase O2 production... Which makes me think the opposite is also true: if Co2 decreases, less oxygen, if light decreases, less oxygen... Possibly then more plant matter dying for adapting to the new, lower light or lower co2 conditions, then more organic matter around, more heterotrophic bacteria, then possibly more BBA.
Click to expand...

If this is true, I think this very important.

If plants release organic carbon when either CO2 and/or light reduce, more organic carbon would be available at the same time less oxygen is available, which is what the heterotrophic bacteria want, but the autotrophic bacteria are unable to cope with.

I tried searching for this on the Internet but couldn't find any references to this happening. It makes sense to me.
 
You must log in or register to reply here.
Back
Top