Plant photosynthesis question: CO2 and Oxygen

Gospel Yev

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I would like to believe that I'm well aware with the photosynthesis process in plants. The leaves and sometimes roots absorb CO2 through the stomata pores and then release oxygen as a a byproduct. All while the plant is receiving sunlight.
However, I've been seeing more and more that plants kind of reverse during no light periods (night) and start absorbing Oxygen instead of CO2.
Am I looking at this correctly? I've seen at Amana Takashi employees turn on the air bubblers at night for the planted tanks to increase oxygen levels while the co2 is turned off at night.

So so do plants really absorb oxygen at night or is it just a very small insignificant thing that I shouldn't be worried about in a planted tank?

Thanks
 

BDpups

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Do you mean Takashi Amano? And you have witnessed employees doing this? Where?
 

TexasDomer

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Unless you're dealing with a CO2 system (and even then it may not be an issue), you don't need to worry about your plants starving your fish of oxygen. I have 4 planted tanks, only one with a sponge filter to create bubbles (no bubblers in any of them), and no issues. I would think the amount is insignificant, and your filter should provide aeration all the time anyway, so I wouldn't worry. If you have a CO2 system, then you might need to worry about too much CO2 and not enough oxygen in the water (but other members can help more with that, I don't have much experience with CO2 systems).
 

Aquaddiction UK

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Plants use O2 24/7 for cellular respiration, but even with high CO2 levels I don't find any signs of low O2 in the mornings. If you have no surface movement then maybe you would notice it a little bit but I wouldn't have a tank without surface movement. This brings in more than enough O2 to keep up with what the plants use (which isn't all that much)
 

ryanr

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Hi, welcome to Fishlore

The short answer to your question is, yes, aquatic plants will consume O2 at night and produce CO2. There's a few threads here about the subject, not to mention countless studies available on the 'net.

With air pumps, it's often recommended to run an air pump overnight when you have one or many of the following:
- CO2 injection with no way of turning off (e.g. DIY CO2)
- Heavily planted aquariums
- Heavily stocked aquariums
- No surface movement at all

Best thing to do is to observe your aquarium, and let it tell you if it needs more O2.
 

Aquaddiction UK

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I much prefer the quietness of surface movement from a spray bar personally, as that is how an air pump adds O2 (through surface movement). This gives optimal O2 without gassing off as much CO2 as an air pump does

Sent from my SM-G900F using Fish Lore Aquarium Fish Forum mobile app
 

ryanr

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I much prefer the quietness of surface movement from a spray bar personally, as that is how an air pump adds O2 (through surface movement). This gives optimal O2 without gassing off as much CO2 as an air pump does
Agreed, air pumps aren't always required.

I can't remember what I was reading quite a few years ago, but there was a hi-light/hi-tech setup where literally NO surface movement was the goal. Due to the high uptake of CO2 required for the specific plants to flourish. Thus, at night, they ran a small air-pump so as to provide some gassing off of CO2. (Wish I could find that setup again, it was awesome).
 

Aquaddiction UK

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No surface movement always used to be the way to go with CO2 enrichment as there isn't as much off gassing of CO2 with a still surface. As time has gone on though, people have turned towards providing a bit of surface movement to ensure there is enough O2 24/7 without the noise of an air pump. It uses a tad more CO2 due to increased gas exchange but the safety barrier is priceless imo. I've had a solenoid jam on for 2 days without me noticing, and surface movement provided more the enough 02 whilst off gassing some CO2 before it got to poisonous levels. Without said surface movement I would have lost a lot of livestock then. Surface movement doesn't gas off as much as an air pump either and is a viable 24/7 option. Amano realised this, hence the lily pipe design for filter outputs.
 

Jomolager

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Hi, welcome to Fishlore


With air pumps, it's often recommended to run an air pump overnight when you have one or many of the following:
- CO2 injection with no way of turning off (e.g. DIY CO2)
- Heavily planted aquariums
- Heavily stocked aquariums
- No surface movement at all

Best thing to do is to observe your aquarium, and let it tell you if it needs more O2.
Is there anything wrong running bubblers or air pumps 24/7?
 

Jomolager

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Is there any reason not to use bubblers 24/7?

Don't mean to hijack the thread, the question arose while reading Mod's post. Sorry.
 

Aquaddiction UK

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You don't need them if you have surface movement from a filter output or powerhead as they both work in the same way (although I much prefer surface movement from a filter outlet personally)
 

BDpups

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Is there any reason not to use bubblers 24/7?

Don't mean to hijack the thread, the question arose while reading Mod's post. Sorry.
Even with pressurized CO2, you can use a airstone 24/7. In a lowlight set up, some suggest using them 24/7.
 

Aquaddiction UK

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Using an air pump alongside CO2 is just a massive waste of gas. You 'can' do it, but it's not the smart option. You won't find an air stone in a single scape entered into the IAPLC and for very good reason.
 

BDpups

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Good to know! But in a medium or high light tank, you wouldn't want the airstone on 24/7 then?
If you like the look of bubbles, you can use them in any planted tank. Low-light, medium-light, high-light. It will not reduce the amount of CO2 to the point of "wasting" it in a pressurized set up. And in a low-light tank, it is said to help bring CO2 from the air into the tank.

Using an air pump alongside CO2 is just a massive waste of gas. You 'can' do it, but it's not the smart option. You won't find an air stone in a single scape entered into the IAPLC and for very good reason.
This is a myth. You can also run CO2 24/7 and not have to worry about gassing off your fish, or "wasting" it.
 

Aquaddiction UK

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Sorry but that just isn't true. If I put an air stone in my high tech tanks now I can guarantee you that CO2 levels will drop by quite a large amount. It actually wastes quite a bit of gas

There is no myth to this what so ever.
 
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