Chemistry/biology questions

[sixty_reefer]

Hi, not sure if anyone knows the answer but what’s your thoughts on the following question.

In an empty cycled aquarium without anaerobic media we’re only nitrate, phosphate and some organic carbon is added. What would be the long term effect on nitrate and phosphate?

Would they eventually recycle from their organic form into inorganic again? Or would they be exported somehow?

No coral, no exports such as protein skimmer or mechanical filtration etc…

My thoughts would be that at some point nitrate and phosphate would accumulate in the system although I’d like a second opinion thanks.

 

[Randy Holmes-Farley Verified Community Expert]

Depends a bit on what organics you are talking about, but assuming it was biodegradable, the N and P will be consumed by and incorporated into bacteria and algae unless something else limits growth (such as a trace element).

 

[sixty_reefer]

Depends a bit on what organics you are talking about, but assuming it was biodegradable, the N and P will be consumed by and incorporated into bacteria and algae unless something else limits growth (such as a trace element).

Thanks, no algae (dark environment).

Do you think that the phosphate assimilation by bacteria eventually would be back into to the water column making eventually a loop?

 

[Tripod1404]

As long as conditions to keep bacteria alive are met, they will be converted into biomass and be locked in that form.

If you continue to dose carbon above its usage rate (i.e. release as CO2) after nitrate are below the levels for bacteria to assimilate, carbon source will start the accumulate and it will eventually reach toxic levels and kill the bacteria, releasing phosphate and nitrate. There can be several cycles of die of and regrowth from the remains, until the environment becomes soo inhospitable that biological activity stops. In that case, much of the organic forms of N and P will very slowly degrade into gaseous forms or sediment/mineralize.

Or alternatively, nitrogen fixing bacteria will colonize the system and form symbiotic relationships with other bacteria. In pockets of biofilm where it is anerobic, they will fix N2 to ammonia and exchange that with carbon that is acquired by bacteria that form and maintain the anerobic biofilm. This will remain stable until P becomes limiting. If no P is introduced and you continue to dose carbon above usage, it will eventually reach toxic levels and kill the bacteria, releasing phosphate and nitrate. Again there will be several cycles or die off and regrowth until biological activity stops and things very slowly degrade to gaseous forms or mineralize.

 

[sixty_reefer]

As long as conditions to keep bacteria alive are met, they will be converted into biomass and be locked in that form.

If you continue to dose carbon above its usage rate (i.e. release as CO2) after nitrate are below the levels for bacteria to assimilate, carbon source will start the accumulate and it will eventually reach toxic levels and kill the bacteria, releasing phosphate and nitrate. There can be several cycles of die of and regrowth from the remains, until the environment becomes soo inhospitable that biological activity stops. In that case, much of the organic forms of N and P will very slowly degrade into gaseous forms or sediment/mineralize.

Or alternatively, nitrogen fixing bacteria will colonize the system and form symbiotic relationships with other bacteria. In pockets of biofilm where it is anerobic, they will fix N2 to ammonia and exchange that with carbon that is acquired by bacteria that form and maintain the anerobic biofilm. This will remain stable until P becomes limiting. If no P is introduced and you continue to dose carbon above usage, it will eventually reach toxic levels and kill the bacteria, releasing phosphate and nitrate. Again there will be several cycles or die off and regrowth until biological activity stops and things very slowly degrade to gaseous forms or mineralize.

Thank you, would this mean that theoretically I could keep producing bacteria consistently and I only would see those nutrients back into the water if they were to die of due to the environment becoming toxic.
Would it be there a ceiling to be hit eventually?

 

[Tripod1404]

Thank you, would this mean that theoretically I could keep producing bacteria consistently and I only would see those nutrients back into the water if they were to die of due to the environment becoming toxic.
Would it be there a ceiling to be hit eventually?

Theoretically, yes. But practically no (unless the goal is to keep bacteria) since we constantly introduce N and P to the system, bacteria population will reach to such high levels that noting else will be able to survive.

 

[Randy Holmes-Farley Verified Community Expert]

Thanks, no algae (dark environment).

Do you think that the phosphate assimilation by bacteria eventually would be back into to the water column making eventually a loop?

Eventually the bacteria will die from lack of organics and the nutrients in them will become inorganic compounds again. Might be years, might be many years, but without some sort of energy input such as light, it must happen.

 

[BeanAnimal]

Algae or not, lack of light does not preclude microbial growth.

This is not a sterile environment and food is being added. Therefore you can't predict what will be introduced or thrive.

Nitrification by nitrifiers may dominate, but given a foothold another set of microbes may take over. They may or may not process nitrate, so the environment could end up going in any direction, including sterile.

The final state is a crap shoot.

 

[Randy Holmes-Farley Verified Community Expert]

Algae or not, lack of light does not preclude microbial growth.

This is not a sterile environment and food is being added. Therefore you can't predict what will be introduced or thrive.

Nitrification by nitrifiers may dominate, but given a foothold another set of microbes may take over. They may or may not process nitrate, so the environment could end up going in any direction, including sterile.

The final state is a crap shoot.

Ultimately, the final state in a nonfed, unlit tank without large localized heat differences is dead everything. It’s a given from the second law of thermodynamics. The complexities of life cannot last.

Every cycle of organics into life forms and back again will be less extensive. Organics will become CO2 and never return fully. Eventually they will all be gone. The last living organism will be very lonely, and when it dies, nothing but chemical reactions will continue.

The deep future for this aquarium is bleak. lol

 

[BeanAnimal]

Ultimately, the final state in a nonfed, unlit tank without large localized heat differences is dead everything. It’s a given from the second law of thermodynamics. The complexities of life cannot last.

Ohh I totally agree. I thought the the premise was continued food input.

The deep future for this aquarium is bleak. lol

Entropy --- the future for the universe is bleak.

 

[Reefering1]

Ultimately, the final state in a nonfed, unlit tank without large localized heat differences is dead everything. It’s a given from the second law of thermodynamics. The complexities of life cannot last.

Every cycle of organics into life forms and back again will be less extensive. Organics will become CO2 and never return fully. Eventually they will all be gone. The last living organism will be very lonely, and when it dies, nothing but chemical reactions will continue.

The deep future for this aquarium is bleak. lol

Because it is missing the input of energy, right?

And I think the goal might be too cultivate the bacteria for feeding purposes, not so much a reef tank situation.(? )

 

[BeanAnimal]

Because it is missing the input of energy, right?

Correct, but even with "energy" there will eventually be a lack of food to sustain life.

And I think the goal might be too cultivate the bacteria for feeding purposes, not so much a reef tank situation.(? )

Bacterial cultures are nothing new -- the question is one of keeping it from becoming contaminated and crashing.

 

[Reefering1]

And I think the goal might be too cultivate the bacteria for feeding purposes, not so much a reef tank situation.(? )

Bacterial cultures are nothing new -- the question is one of keeping it from becoming contaminated and crashing.

That was my assumption of intent, it wasn't clearly stated- but, imo, it clearly isn't a running reef tank.

(?)

 

[Reefering1]

Correct, but even with "energy" there will eventually be a lack of food to sustain life.

Right, but if we feed c/n/p, is it sustainable?

 

[sixty_reefer]

Theoretically, yes. But practically no (unless the goal is to keep bacteria) since we constantly introduce N and P to the system, bacteria population will reach to such high levels that noting else will be able to survive.

Thank you, I was contemplating if there was a way to calculate if the input of nutrients to feed the bacteria could be used as an indicator for a Protozoa culture being consumed by a NPS organism.
My thoughts were if I would see a constant need to keep adding nutrients as a possible sign that the bacteria and Protozoa was being consumed.
and if I was to see a build up of phosphate or nitrate as a indicator that the pathway not working.

I may have to look for a different way to quantify this as it seems this may not work as I thought

 

[sixty_reefer]

Eventually the bacteria will die from lack of organics and the nutrients in them will become inorganic compounds again. Might be years, might be many years, but without some sort of energy input such as light, it must happen.

Thank you, I thought that heterotrophic organisms would take their energy from organic carbon. Light would only be essential for photosynthetic organisms.

 

[sixty_reefer]

Because it is missing the input of energy, right?

And I think the goal might be too cultivate the bacteria for feeding purposes, not so much a reef tank situation.(? )

Yes, I was wondering if I could use the phosphate cycle as an indicator of usage.
It seem that it won’t be possible.

 

[BeanAnimal]

This appears to be the same discussion as before, just reframed.

The flaw in the assumption has not changed. These are not simple pathways that are going to follow a fixed ratio.

 

[BeanAnimal]

Are you trying to grow food, or is this an experiment?

 

[sixty_reefer]

Are you trying to grow food, or is this an experiment?

I’m trying to replicate the lowest tropic levels in the sea in an aquarium. A little of both really.