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co2 for plants

This is a discussion on co2 for plants within the Beginner Planted Aquarium forums, part of the Beginner Freshwater Aquarium category; --> Originally Posted by aokashi I've never seen a CO2 diffuser that creates significant turbulance. The flow should not be allowed to be that great ...

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Old 01-30-2013, 06:25 PM   #11
 
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Originally Posted by aokashi View Post
I've never seen a CO2 diffuser that creates significant turbulance. The flow should not be allowed to be that great either. If CO2 diffuser created water distubance, it will defeat the purpose of CO2 injection and prove to be counter productive....

The scenario is basically replacing a CO2 tank with something like an airpump and a control valve that brings in atmospheric air at a controlled rate...

does that make more sense or are you still thinking airpumps, airstones and lots of water movement?
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This confuses me. Isn't atmospheric air what is pumped into the tank by an air pump attached to an air stone or bubble wand, etc? Why would what you are suggesting be any different?

Last edited by Byron; 01-30-2013 at 06:51 PM.. Reason: spelling
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Old 01-30-2013, 06:35 PM   #12
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Originally Posted by aokashi View Post
I've never seen a CO2 diffuser that creates significant turbulance. The flow should not be allowed to be that great either. If CO2 diffuser created water distubance, it will defeat the purpose of CO2 injection and prove to be counter productive....

The scenario is basically replacing a CO2 tank with something like an airpump and a control valve that brings in atmospheric air at a controlled rate...

does that make more sense or are you still thinking airpumps, airstones and lots of water movement?
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I didn't say turbulence, I said disturbance. I understand exactly what you are describing. All that is different is that you are going to try to create much smaller bubbles, these are a disturbance by their very nature in the water column. They are little pockets of air and will still absorb CO2 from the water the exact same as air sitting above the still surface or air being forced through the water while being shaken in a jar. The only difference is that as the bubbles get smaller and more numerous given the same volume of air injected, you create a larger surface area for this transfer to take place. It's not actually the disturbance itself, it's the presence of the air in that space.

Here's another way to look at it.

Consider that a CO2 bubbler adds bubbles that are close to 1,000,000 ppm CO2 whereas air, even from a highly carbonated residence might reach 1,000 ppm. If a CO2 bubbler might add a few ppm (I'm not certain how much but I would guess maybe as much as 5ppm, more than that would start harming the fish) to the water based on a 1,000 times greater concentration of pure CO2 than in air... What the heck do you expect to inject from air? It is somewhere around 800,000 ppm nitrogen....

Even the relative math doesn't allow for it to work.

Go ahead and try it out, just be sure to test properly so you know what is happening... I can already guess the results though.

Jeff
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Old 01-30-2013, 07:29 PM   #13
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techinically 30ppm...
which will grow practically all aquarium plants with the right light and fertilization...
which means ar 20ppm above normal levels many plants will grow at a visually obvious rate...
but nvm, lol.

if you've ever seen a CO2 setup, you can see that CO2 that is diffused will dissolve slowly into the water column...rater than absorb....
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Old 01-30-2013, 08:01 PM   #14
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Originally Posted by aokashi View Post
techinically 30ppm...
which will grow practically all aquarium plants with the right light and fertilization...
Sure, but kill the fish... I know I know, you said fishless. I think that the right light and ferts can be made work for the vast majority of plants without ever getting into CO2 injection in the first place.

Isn't there a point where CO2 is harmful to the plants as well?

Jeff.
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Old 01-30-2013, 08:14 PM   #15
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you can hardly kill fish with 30ppm co2 or ferts... or light(?!?!)
heck you can't even kill shrimp if done properly. and it is done by planted tank enthusiasts all around the world. ADA has it down to a refined art...And it is also done by the people around me. and these people keeps shrimps of all varieties, not just with neos, with caridinas too. anything is toxic at a certain point... even oxygen for humans. Plants dont use CO2 at night so it is possible that they will die if they don't have access to oxygen at night. CO2 is also usually shut off at night because of this.
I'm running my own experiments with high light tanks without CO2. And I've found that I can grow the majority of plants including the fussier carpeting ones with 60PAR at substrate level, good flow and ferts dosed. But although my plants grow heathily and steadily, they cannot meet with the accelerate growth boost my fellow aquarists manage with CO2 injection.
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Old 01-30-2013, 08:19 PM   #16
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Originally Posted by Byron View Post
This confuses me. Isn't atmospheric air what is pumped into the tank by an air pump attached to an air stone or bubble wand, etc? Why would what you are suggesting be any different?
because the bubbles are too big and travelling at a speed too vigorous to be dissolved into the water column...
Same reason why an airpump doesnt oxygenate the water via the air it generates....
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Old 01-30-2013, 10:15 PM   #17
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Originally Posted by aokashi View Post
you can hardly kill fish with 30ppm co2 or ferts... or light(?!?!)
heck you can't even kill shrimp if done properly
Yes, I had the relative number right and the absolute wrong.

My point remains, you can't increase CO2 by injecting air in any manner. It may also not reduce it beyond the current equilibrium levels but it will serve to remove anything over that level. Air is air and altering how you pump air into the water will not change the tendency of water to release CO2 into the air.

You suggest that you are possibly able to do so by changing the method of delivery by decreasing bubble size in an effort to reduce "turbulence". Please post your results of the experiment.

I think that we hijacked this thread long enough with our argument (sorry Squish)... there's already enough thread hijacking lately.

Side note:
I happened to stumble upon a chart for determining how much CO2 may be contained in the water based on the pH and KH. My KH is just off the chart but it would appear that I am just under 10ppm. Not exactly sure how accurate that method is but it is interesting in its relative application.

Jeff.
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Old 01-30-2013, 10:21 PM   #18
 
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the good co2 Diffusers don't make many bubbles, and are designed to keep co2 in contact with the water with a membrane of some sort. they don't work like the airstones people use. Air passes through an airstone fairly easily and bubbles out. Diffusers try to hold the co2, and the excess bubbles out.
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Old 01-30-2013, 10:26 PM   #19
 
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Woahwoahwoahwoawoa...
This discussion is getting way too technical and sciencey. I'm totally lost. Basically The message I got is that It's waaaaaaaaaaaaaaay too complicated, so I should toss that Idea. Does a heavily planted tank really need the extra co2? Is the only reason people add co2 because algae thrives in low co2 environments? So, can the plants still thrive in low co2, cuz algae is NOT an issue: I LOVE algae-eaters.
Thanks!
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Old 01-31-2013, 12:18 AM   #20
 
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I'm actually ready to try out diffusing atmospheric air in tank water. Theoretically it should work. and if it does, it's a lot cheaper than a CO2 setup and doing refills.

like I was trying to explain to someone before atmospheric air (especially in a room) can have up to 3000ppm of CO2....
Theoretically? No.

You may want to study up on Henry's Law: "At a constant temperature, the amount of a given gas dissolved in a given type and volume of liquid is directly proportional to the partial pressure of that gas in equilibrium with that liquid."

The partial pressure of CO2 in air is about 0.04% of the total pressure so I'm confused how you have any reason to believe this would work. Think about it; even those of us that are using pure CO2 are still trying to design better methods for more efficient dissolution of the CO2 into water. We've got rex rigs, cerges reactors, ladders, bells, and many others, yet the hunt may never be over. I hope you understand the dead end you're running into and just save yourself some time and effort.
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