The importance of constant 24/7 Co2 for nitrifying bacteria colonies

1896 Views 7 Replies 7 Participants Last post by lksdrinker, Oct 21, 2016

IUnknown

Discussion Starter · Oct 13, 2016

I had not realized that the bacteria in our tanks utilize the Co2 in our tanks. The thread below (haven't read all the way through) is interesting. I had always set my Co2 to turn off at night so it didn't get wasted. But looks like that was wrong as it might affect my bacteria colonies. Haven't stable Co2 all the time looks like an important part of keeping algae under control.

What exactly causes BBA? Part 2 - Bacterial imbalance | UK Aquatic Plant Society

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Clinton Parsons

· #2 · Oct 13, 2016 (Edited)

I skimmed the linked page and am not seeing what makes you say this. Looks like there are 25 pages. Did you mean to link to a different page in that thread?

Are you talking about the line about co2/bicarbonate availability, and low level co2 ensuring bicarbonate availability? You are always going to have bicarbonate buffering going on if you have some discernible carbonate reading, unless you are using new active substrate, not adding buffers, and using carbonate-free water. Your plants are going to respire O2 at night, dissipating co2 back into the water if you are concerned about that acting on the carbonate/bicarb... you are always going to have some co2.

I just don't see where you are getting all of this from. If you want to help your bacterial colonies, the higher pH and higher aeration that happens when you raise your pipe a little and cut off the co2 will do you very well.

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roadmaster

· #3 · Oct 13, 2016

Oxygen is much more important to the tank than CO2.
Everything living in the tank,, from bacteria, to fauna,to plant's need/use considerable amount of O2 to survive.

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Jeff5614

· #4 · Oct 13, 2016

Maybe you could direct us to the page or post number, please. I've read that thread in the past and I'm not keen to reread all 25 pages if it's not necessary.

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IUnknown

Discussion Starter · #5 · Oct 14, 2016

The main reason, I think, why nitrification is inhibited at low ph(6.5 and below) is because there's very little ammonia at that ph. Nitrifying bacteria uses ammonia and not ammonium for nitrification. When there's none or little, their population dwindles to match availability.

This is interesting. How about taking it from the angle of starving algae off ammonia. If you let the ph raise, you increase ammonia. So another plus to leaving Co2 24/7.

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g4search

· #6 · Oct 17, 2016

From a chemical point of view this is just entire nonsense. Everybody knows that adding CO2 to your tank LOWERS the pH (because indirectly you are adding "carbonic acid." The lowest possible pH attainable with CO2 is 5.5) The more divalent ions (magnesium, calcium, etc. you have in your water will result in higher pH, because these basic metal ions will function as buffer. Therefore, under real life conditions, the pH in your tank (with added CO2) will be somewhere between 6 to 7.2!
At this pH, the concentration of ammonia (NH3) is minimal, since most of the ammonia present will exist in its ammonium (NH4)+ form.

Turning CO2 off at night will only increase the pH value (typically from 6.5 to 7.5). An increase in pH will impact the equlibrium between ammonium ions (NH4)+ and ammonia (NH3) in favor of ammonia. This means that the nitrifying bacteria have more of desired ammonia (NH3) available when no CO2 is added to the tank.

From a biological point of view this entire discussion is moot, because all nitrifying bacteria can adjust to the prevailing pH and can convert ammonium ions to ammonia as needed. The bacteria use this biological oxidation process to convert ammonia to nitrate and obtain energy from it. Actually, temperature is the more important factor for this process.
Under NORMAL tank conditions you just CANNOT STARVE nitrifying cultures of ammonia.

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klibs

· #7 · Oct 19, 2016

tldr:

ehhhhh i'm not so sure about that...

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lksdrinker

· #8 · Oct 21, 2016

IUnknown said:
I had always set my Co2 to turn off at night so it didn't get wasted. But looks like that was wrong as it might affect my bacteria colonies. Haven't stable Co2 all the time looks like an important part of keeping algae under control.

Are you saying you were wrong to do this because you saw something happening to make you think you were loosing the beneficial bacterial colony? Or because you read something someone wrote on the internet? Unless your bacterial colony was crashing I'm not sure why you'd think you were encountering any sort of problem?

Turning the co2 off at night is done not only to avoid wasting it but to prevent the potential gassing of fish. Plants are not uptaking the co2 when the lights are off; and I presume algae isn't either. So if you keep adding co2 while the lights are off and the plants are not "consuming" it you run the risk of killing off fish.

Having stable co2 is essential. But I think the idea is to keep the co2 levels stable for the period of time that it is actually being injected.

I have to wonder if there is some confusion as to the type of co2 setup as well. Inconsistent co2 levels seems more common with the DIY methods as opposed to injecting pressurized co2 (assuming a decent needle valve is used anyway).

g4search said:
From a biological point of view this entire discussion is moot, because all nitrifying bacteria can adjust to the prevailing pH and can convert ammonium ions to ammonia as needed. The bacteria use this biological oxidation process to convert ammonia to nitrate and obtain energy from it. Actually, temperature is the more important factor for this process.
Under NORMAL tank conditions you just CANNOT STARVE nitrifying cultures of ammonia.

All very interesting. I'm wondering though about the temperature. Is there an ideal temp for the process to work best? Any idea what the highest and lowest points would be?

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