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Re: [APD] CO2 mist and theories, laws, and misapplied research
Thomas Barr wrote:
> The CO2 reactor will fill up with CO2 gas daily as the day
> progresses and when the reactors are turned on every morning,
> will quickly dissolve the gas bubble (from the previous day)
> rapidly(typically less than one minute for most reactors).
> People can see that.
I see some gas build up in there, but I am totally unable to visually
determine that it is CO2. Is there something I might be missing perhaps?
> You can purge the gas bubble out and fill with CO2 from your
> tank to this same level(mark the reactor tube) and time the
> amount of time it takes to dissolve. I also have O2 gas and
> measured the same amount of O2 gas to dissolve(over an hour).
> Some suggested a hard to dissolve contaminant gas, yet the next
> morning it rapidly dissolves, depresses pH and has the same rate
> of dissolution as CO2 gas. Maybe there is some magic gas that
> behaves like CO2 in terms of dissolution rate, reduces the pH,
> and also increases plant growth. If someone knows of such gas,
> I'm all ears and will gladly eat some crow.
It has already been explained by many people ad naseum at
plantedtank.net and here that O2 and N2 diffusion will explain this
phenomena without requiring the suspension of other known laws.
> That is repeatble and easy to see.
> That is something folks can and have seen many times(not just
> me). By comparison, O2 took 92 times longer to dissolve at
> ambient saturated O2 levels vs CO2(average time was 41 secs with
> 7 trials, SD +,- 3 sec, O2 took much longer, over an hour). You
> can also watch the bubbles from a disc diffuser float up and
> dissolve before they rise to the surface in the AM and later in
> the day watch them persist much longer (PM). While there is an
> issue with O2 bubbles popping in the mix from the plants, simply
> following the bubbles right from the diffuser on out and then
> doing the same when they dissappear eariler addresses that.
> Also, adding pure O2 to the disc duffusers and seeing how little
> dissolves will give an indication that the bubbles floating
> around are not O2. Measuring the DO levels with a test kit also
> addresses whether you have more pearling with a method/treatment
> or not. That is a stanard method for submersed plants and algae
> growth productivity measurements.
I am not sure why you are confusing the process by which O2 dissolves
into solution with the process by which it is driven out. In short, no,
that O2 dissolves slowly does not suggest that O2 is not diffusing into
CO2 bubbles later in the day after O2 is saturated and begins to diffuse
out of the water at *any* air/water boundary. In fact, that O2 is so
reluctant to dissolve in water is one reason why it wants to get out so
The easy way to answer this question once and for all is to capture some
of these bubbles and expose them to a solution of calcium hydroxide.
Chalky water equals CO2, otherwise there isn't any.
> If it is not CO2 that accumulates, then how does the pH drop,how
> does that gas dissolve so well yet is also at the same time a
> gas that does not dissolve and accumulates, why does the O2
> levels increase and why do the plants grow better and pearl
"How does CO2 dissolve so well, yet not disolve so well?" That seems to
be what you are asking, but it doesn't make any sense to me.
As to why the O2 level increases and plants grow better and pearl sooner
- that's what we all want to know. Some already well-established
principles suggest that it is not because CO2 is not dissolving after 30
mg/L. Since we know nothing about the tests and the controls, we don't
even have a way to theorize.
> These are things folks can (and have) see and measure.
> I suggest folks try it. Does not cost much to try it, folks with
> external reactors can use it, internals, or disc.
> If you also look nearest the outflow of a CO2 reactor, the
> plants always pearl more and sooner even though the tank is
> supposedly well mixed(the ppm of CO2 is the same at both ends of
> the tank).
> I've wondered how there can be patchiness/zonation in the amount
> of pearling of similar plants further away from the reactor but
> the same CO2 ppm in the water test. Dissolved CO2 can be well
> mixed but the bubble mist is not. Changing the flow so that the
> mist goes all over and measuring the ppm of CO2 is relatively
> All you have to do is look, try it and think about it.
> Prove it to yourself with the observation first. Just try it.
Yet again: no one is trying to say you aren't seeing better
growth/pearling. We are question the mechanism by which this occurs.
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