Plant photosynthesis question: CO2 and Oxygen

BDpups

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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.
Ever try it? It's not like CO2 is expensive. If you think you are wasting it by running an airstone, increase the CO2 by about 1 BPS. It will counter act what gassing off is being done. It will not drop your CO2 levels "by a large amount".

Since it sounds as if you have tried this, what is that large amount? 10ppm? 20ppm?

Personally I would not run an air-stone just because I don't like the look of them. But as far as it wasting CO2, this is just not true.
 

Aquaddiction UK

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So..
When fish are being poisoned by CO2, an air stone doesn't almost immediately reduce the CO2 level, no? I know an exponential number of people that would strongly disagree. An air stone makes a big difference - by breaking surface tension. Have you never shook a bottle of carbonated drink? What happened then? Ever added an air stone to a high tech tank and watched the pH fall? 1 bps could mean double your CO2 usage on a small tank, and you'll need more than an extra 1bps when running an air stone in a bigger tank. An air stone 100% unequivocally reduces CO2 content in the water and is 100% not needed
 

BDpups

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So..
When fish are being poisoned by CO2, an air stone doesn't almost immediately reduce the CO2 level, no? I know an exponential number of people that would strongly disagree. An air stone makes a big difference - by breaking surface tension. Have you never shook a bottle of carbonated drink? What happened then? Ever added an air stone to a high tech tank and watched the pH fall? 1 bps could mean double your CO2 usage on a small tank, and you'll need more than an extra 1bps when running an air stone in a bigger tank. An air stone 100% unequivocally reduces CO2 content in the water and is 100% not needed
I never said it was needed. I said it will not waste CO2. And no, adding an air-stone to a tank with fish being suffocated by CO2 will not immediately help them. It does not introduce oxygen into the tank fast enough. I've done this myself. Have you?

Adding an air-stone to a tank with CO2 would raise the PH. Not lower it.

CO2 must be very expenisve for you. If I actually had to double the amount I use, it would cost an extra $25 a year. A small price to pay if I wanted bubbles in my CO2 tanks.
 

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By the way, an air stone works against poisoning by releasing CO2, not by adding more O2. If you're aware of pearling then you will be aware that plants only visually pearl when the water is fully saturated with O2, therefore it is literally impossible to add any more O2 with an air stone. You cannot supersaturate with an air stone. The laws of science deems it impossible. This in itself is proof that an air stone gasses off CO2.
 

ryanr

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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.
For the reasons mentioned above, yes there is a reason not to run 24/7. That is, to maximise CO2 concentration during lights on (while the plants are photosynthesising). But equally, if you run them 24/7, you may need to increase the amount of CO2 being injected (be it gas or liquid)

Using an air pump alongside CO2 is just a massive waste of gas. You 'can' do it, but it's not the smart option.
Agreed.

If you're aware of pearling then you will be aware that plants only visually pearl when the water is fully saturated with O2, therefore it is literally impossible to add any more O2 with an air stone. You cannot supersaturate with an air stone.
Small clarification.... Pearling is a result of 'perfect' levels of light and CO2, allowing the plants to be at maximum metabolic rate. Producing oxygen faster than it can be dissolved into the water column. It doesn't always indicate total/maximum O2 saturation, but often is the case.

Also - and we're getting into a lot of science. Water temperature will also have an impact on the dissolved oxygen capability of the water. Warmer water holds 'less' oxygen - hence why air pumps are recommended when temperatures rise.

Adding an air-stone to a tank with CO2 would raise the PH. Not lower it.
Correct. CO2 produces a weak acid, which can lead to pH drops. Depending of course on the buffering capacity of the water, temperature etc. Thus, increasing O2 could either balance the effect of CO2 or raise the pH.
Typically, assuming the buffer capacity of the water is adequate, the effect is subtle, gradual and poses no risk to livestock.

Let's keep the conversation civil. There's no need for personal attacks.
 

BDpups

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By the way, an air stone works against poisoning by releasing CO2, not by adding more O2. If you're aware of pearling then you will be aware that plants only visually pearl when the water is fully saturated with O2, therefore it is literally impossible to add any more O2 with an air stone. You cannot supersaturate with an air stone. The laws of science deems it impossible. This in itself is proof that an air stone gasses off CO2.
No one has said an air stone does not gas off CO2. It just does not do it to the effect that it will negatively impact the plant growth. And if it is, just add a little more CO2. Pretty simple.
 

Aquaddiction UK

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Although yes it's true that pearling (oxygen) is a waste product of photosynthesis and is visible when it is produced faster, you only see visible bubbles when no more oxygen can be dissolved into the water (fully saturated). Hence low tech plants pearling after a water change (water is temporarily saturated with more O2), and why a high tech tank starts to pearl a while after 'perfect' conditions have been provided. You can create pearling with sub optimal CO2 levels.
 
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Gospel Yev

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Do you mean Takashi Amano? And you have witnessed employees doing this? Where?
Yes, one of ADA's videos on YouTube showed them lifting the outflow pipe on the evening after lights off to create aeration.
 
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Gospel Yev

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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.
I run pressurized CO2 but I have great water movement. (In the form of a long U down the long side of the tank)
i guess I won't worry about O2 then. I turn the co2 off after lights off. I just thought maybe in the process of photosynthesis, plants reverse during the night and consume O2 rather than Co2.

Thanks!
 
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