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[APD] CO2 mist and theories, laws, and misapplied research

Let us review a few things here that many smart folks suggested
in the past both here and most every forum and see how they have
changed through time:

Example 1
Liebig's Law of Minmum many years ago here/elsewhere. They
claimed that what was causing algae was excess PO4, non
limitation(see Sears Conlin paper). We discovered that NOT to be
true(PO4, NO3, Fe etc). Misapplied. Aquatic plant scientist
already knew that when you add more PO4 to a heavily planted
lake, you get more plants, not algae. No surprise for them.

Algae are not nutrient limited in our tanks. Everyone said I was
wrong, what I was saying was dangerous but clearly at the
nutrient levels, the health status and lack of algae in my and
most folk's tanks, this cannot be the case.
I also provided several mechanisms as to why that was.
I provided uptake rates and folks could see dramatic pearling by
adding PO4 within about 40-60 minutes after adding PO4 to their
tanks, as well as a reduction in Green spot algae and better
growth of a number of tougher to grow plants. 

I got poo pooed on these list/forums for saying all this (but
not in the cohorts that actually study the aquatic weeds) but I
knew I was right with my initial observation.
Basic observations are where science starts, not a misapplied
theory nor premade conclusions. One should never assume that the
principles and theories are always correct and thus should
maintain an openess to question the application as well.
You need to explain the observations as best you can. 

So it would not be the first time folks have been wrong with a
seemingly nutty idea that flies in the face of "known scientific

Example 2: 

People use to say and many still do that pH swings cause fish
kills and problems with their health, yet anyone can do a large
water change using CO2 and see a swing of a full unit without
issue, week after week. Also flies in the face of principles and
was based on speculation, NOT actually testing the specific case
in question(CO2 influenced pH levels). 

That myth was applied to past advice from adding dramatic KH/GH
changes. Today we know that adding lots of baking soda suddenly
can kill fish but it has little to do with CO2's effect on pH.
We change that pH every week and can and do easily repeat the

I have plenty more examples that I have addressed over a long
time frame and not just freshwater plants, but marine systems
and lakes, streams, wetlands.........  
Let's look at what we do know:

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. 

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.  

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.

When folks put a venturi loop on a sump reactor that purges the
CO2 gas build up, they have a decrease of the pH with no change
to the CO2 gas rate of .3-.4 pH units. Then they can take the
loop off, seal the inlet and the pH goes up.   
Folks can watch and see this repeatedly. 

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

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.

Tom Barr


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