Oxygen reactor?

[RonS]

OK, so this is probably something that's come up before and already been debunked, but I was "thinking" this morning (dangerous!!)...

I've had issues keeping my pH high enough. I don't have convenient access to outside "fresh" air. I bought a cheap media container and put some CDX in it, and plumbed it to the intake on my skimmer. I immediately saw a marked improvement in pH. That is, of course, until the media ages out, then you have a bit of a roller-coaster.

My hypothesis... the excess CO2 in interior air is largely displacing 02, and that it's this drop in O2 that is responsible for the depressed pH levels. If that's the case, rather than scrubbing CO2 from the intake air, why not inject some pure O2 into the intake? This O2 would displace some of the intake air, and thus increase the overall O2 at the skimmer intake (with a corresponding decrease in intake CO2).

What am I missing? I would much rather change a small oxy bottle every few weeks than to buy / mess with scrubber media. I would imagine one problem may be that I'm grossly underestimating the amount of O2 needed, which would nip a harebrained scheme like this in the but pretty quickly. I know - electrolysis!! (Look for my next post on what to do with all my excess hydrogen

Thoughts are appreciated...

--Ron

 

[Eric_n_Ga]

Might be easier to add a bigger co2 scrubber , vs an 02 bottle . Plus you can order media online vs finding a medical grade O2 supplier without a medical reason. Only reason I say that is I was using pure oxygen for another reason and I was having problems getting them filled.

 

[RonS]

Well, the CO2 media is NOT cheap, which is why I'm curious about adding O2 (in case it's cheaper - dunno!!). I live very close to a welding supply shop, and I refill O2/propane/acetylene bottles there fairly regularly. But that's an excellent point about medical grade O2 - who knows what they're putting in a welding bottle?!??!!

Any thoughts on the original premise of adding O2 to offset CO2 and thus increase pH? Have you done this / seen it done?

Thanks!

 

[Eric_n_Ga]

Welding bottles are steel ,medical grade O2 bottles are aluminum. Something else to keep in mind

 

[ichthyoid]

What causes the drop in pH is CO2, not O2.

First, CO2 is much more soluble in water than O2 is.

When CO2 dissolves in water, it spontaneously ionizes and forms carbonic acid. This carbonic acid, while being a weak acid, does cause a decrease in the pH of the water.

For example:
If we were to fill a clean water glass with pure 0 TDS deionized water, CO2 from the surrounding air would soon begin dissolving into the water on it‘s own. The result, as mentioned above, would be a drop in pH. This mechanism is controlled by laws of physics.

CO2 also plays an important role in carbonate-bicarbonate chemistry in reef aquariums. Limiting the available CO2 serves to drive the balance of the reaction towards bicarbonate and a higher pH.

 

[ichthyoid]

Edit:
The last paragraph should read-
...drive the reaction toward carbonate and a higher pH.

 

[ichthyoid]

 

[bhodges82]

Co2 lowers pH, o2 doesn't raise pH.

Sorry.

 

[Adam]

I had thought of this too when I first started in the hobby. I use it with baitfish why not the aquarium too? But in essence it's a bad idea. It just doesn't work that way. Oxygen O2 does not absorb or remove co2 from the water column, air does. Oxygen is only 21% of air molecules. 78% of air is Nitrogen and the chains in the molecules is what allows co2 to be absorbed. Among small amounts of other gasses like argon.

By introducing pure O2 into the system you will increase the dissolved oxygen, over time as O2 is not as soluble in water as co2 or air, to to point the it could become toxic and potentially fatal if not monitored or if too much is released. Throughout this happening there will be no change to the co2 level in the system. In fact the co2 could start rising through the increased metabolism of the occupants due to the extremely high O2.

With the baitfish system I use, the bubble size is very, very small, almost micro bubble sized. This gives you a lot more surface area to the O2 so the absorption rate is higher. We like to call it herring crack.

 

[Eric_n_Ga]

I had thought of this too when I first started in the hobby. I use it with baitfish why not the aquarium too? But in essence its it's a bad idea. It just doesn't work that way. Oxygen O2 does not absorb or remove co2 from the water column, air does. Oxygen is only 21% of air molecules. 78% of air is Nitrogen and the chains in the molecules is what allows co2 to be absorbed. Among small amounts of other gasses like argon.

By introducing pure O2 into the system you will increase the dissolved oxygen, over time as O2 is not as soluble in water as co2 or air, to to point the it could become toxic and potentially fatal if not monitored or if too much is released. Throughout this happening there will be no change to the co2 level in the system. In fact the co2 could start rising through the increased metabolism of the occupants due to the extremely high O2.

With the baitfish system I use, the bubble size is very, very small, almost micro bubble sized. This gives you a lot more surface area to the O2 so the absorption rate is higher. We like to call it herring crack.

I stopped using it on the boat all together. Not worth it.

 

[Adam]

I stopped using it on the boat all together. Not worth it.

Since I have it I figured I'd still use it. But very sparingly now. Couple times durning the trip for only a few minutes while still using the normal aeration of the bait tank.

 

[RonS]

Thanks, all!

Well, that was dumb - I know that it's excess CO2 and not a lack of O2 that's the issue.

What I was getting at is that the excess CO2 in the living space is going to be largely due to a combination of human respiration and furnace combustion byproducts (among a million other things, but I see these as the primary culprits). Neither of those processes alter the nitrogen and other air components significantly. E.g., for there to be excess CO2, there is likely a corresponding decrease in free O2. I am advocating dosing a small enough amount of O2 to "dilute" some of the Co2, and simultaneously raise the incoming O2 to nominal levels. That would, of course, reduce the concentration of nitrogen and other gasses as well, but could it be worth it?

I had also thought about using nitrogen gas, but I assumed that could seriously mess with the cycle within the tank (but I won't pretend to understand what role free Nitrogen plays in that process!). Maybe I can just fill a bottle using my air compressor with outside air as the source

Again, just thinking out loud. Thank you for indulging me!

--Ron

 

[Eric_n_Ga]

I had to add a pump to skimmer to get it to do what I needed. I currently have my air pump in the bottom of a Tupperware container full of zeolite with holes on the lid . I can fit a lb of media in the container and it seems to last longer

 

[RonS]

I had to add a pump to skimmer to get it to do what I needed. I currently have my air pump in the bottom of a Tupperware container full of zeolite with holes on the lid . I can fit a lb of media in the container and it seems to last longer

Interesting! So, the output of the air pump is connected to the intake/silencer on your skimmer? Kind of a zeolite super charger?

 

[Adam]

With the bait tank use of O2, I'm sure the reason Eric stopped using it is the same reason I severely cut back on how much I use it. At the end of the day the water in my 30 gallon bait tank was so fouled it was dirty milky looking and stunk to the high heavens. We drove the poor fishes metabolism through the roof. Now I like to use just a little to make them more active when I drop the bait down. But he's on the water a whole lot more than I've ever been.

Here's some articles & threads that have some relevance to the topic.

Quick primer on how o2 levels affect co2 in the reef tank

Randy I had a question as to whether or not oxygen saturation reduces co2 in aqueous solutions by physical exclusion im under the impression it does not...the partial gas pressure for co2 is what determines co2 levels and it functions independently of oxygen saturation at our common temps From...

www.reef2reef.com

O2 and CO2 - Reef Central Online Community

O2 and CO2 The Reef Chemistry Forum

www.reefcentral.com

Has anyone dosed O2 into your tank? - Reef Central Online Community

Has anyone dosed O2 into your tank? Advanced Topics

www.reefcentral.com

Aquarium Frontiers Library

https://www.google.com/url?sa=t&sou...FjAPegQIAhAB&usg=AOvVaw1_RfGzAKvJfEw1apioja9L

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[RonS]

That last Reef Central post is perfect - thank you!! I was clueless as to the massive disproportion in air concentrations between O2 and CO2. I'll be sticking with my scrubber, then : )

Thanks again!!