Addition of CO2 ?

[KansasNative]

You hypothesis of occurrence of some specified group of phenomena, either asserted merely as a provisional conjecture to guide investigation (working hypothesis) or accepted as highly probable in the light of established facts was nicely put. I do agree somewhat, but of course it is all speculation. I desire to perform a practical application. It will not be scientific, just the addition of CO2 and then by simple visual inspection, during a specific time, determine if the results are of a positive nature. :?:

I do know that pro algae growers for biodiesel supplement with CO2 for best results. Again, I think if you off gas prior to the waters return to main tank, PH should not be an issue, considering the buffering capaicty with the high KH content of saltwater or in a hardwater tank , as is my case.

Anyway, it is just a hobby for fun, and fun to experiment with and something to do. I am not a scientist, nor biologist, just a retired hunter.

I like your contributions - thanks. :mrgreen:

[KansasNative]

Oh, and the release of CO2 when the surface tension of the water is disturbed is greater then the addition of O2 due to lack of dwell time of the bubbles before reaching the surface. Anyway that is what my micro-biologist friend tells me. What does I know, DUH.

Now if you want to talk about aerodynamics; dissymmetry of lift, retreating blade stall, gyroscopic procession, transverse flow effect, relative wind or Bernoulli's principle, then I'm ready.

Aint't this fun ? :?:

[Amphiprion]

That will certainly have some contributory effect. I think the following site summarizes it nicely: http://www.gewater.com/handbook/ext_tre ... ration.jsp

Agreed. There's only one way to find out if it helps or not and that is to do it.

FWIW, much of those principles you mentioned can also be applied to hydrodynamics, of course with different constants. Kinda interesting how similar they can be, minus a few numbers :lol:

[KansasNative]

This is what I gathered from the GE website:

The efficiency of aeration is greater where the concentration of the gas to be removed is high in the water (CO2 from fish expiration) and lower in the atmosphere. Consequently, the establishment of a state of equilibrium between water and air by means of aeration results in saturation of the water with nitrogen and oxygen and nearly complete removal of other gases, (i.e. CO2). :shock:

Why I think it would be advantageous to add CO2:

The basic requirements for the growth of algae: nitrogen + carbon dioxide + light energy = glucose + oxygen

Algae photosynthetic efficiency varies with the frequency of the light being converted, light intensity, temperature, proportion of carbon dioxide and nitrogen. As carbon dioxide concentrations rise, the rate at which sugars are made by the light-independent reactions increases.

RuBisCO (Ribulose-1,5-bisphosphate carboxylase oxygenase), or the enzyme that captures carbon dioxide in the light-independent reactions, has a binding affinity for both carbon dioxide and oxygen. Since carbon dioxide and oxygen compete at the active site of RuBisCO, carbon fixation by RuBisCO can be enhanced by increasing the carbon dioxide level in the compartment containing RuBisCO (chloroplast stroma).

When the concentration of carbon dioxide is high, RuBisCO will fix carbon dioxide. However, if the carbon dioxide concentration is low, RuBisCO will bind oxygen instead of carbon dioxide. This process, called photorespiration, uses energy, but does not produce sugars. Therefore reduced growth is the result.

Some enzymes typically can carry out thousands of chemical reactions each second. However, RuBisCO is slow, being able to "fix" only 3 carbon dioxide molecules each second. Nevertheless, because of its extremely large concentration, under most conditions, and when light is not otherwise limiting photosynthesis, the reaction of RuBisCO responds positively to increasing carbon dioxide concentration; therefore the concentration of carbon dioxide is the limiting factor.

Upon illumination of the chloroplasts, the pH of the stroma rises from 7.0 to 8.0 because of the proton (hydrogen ion, H+) gradient created across the thylakoid membrane. At the same time, magnesium ions (Mg2+) move out of the thylakoids, increasing the concentration of magnesium in the stroma of the chloroplasts. RuBisCO has a high optimal pH (can be >9.0, depending on the magnesium ion concentration) and thus becomes "activated" by the addition of carbon dioxide.

FINI :mrgreen:

[Amphiprion]

What you are still not seeing is that despite the fact that CO2 levels are lowered substantially by aeration, there will always be ambient concentrations. That translates, for a scrubber at least, to a near-unlimited, albeit low, supply of CO2. Unlike algal ponds like you were suggesting earlier, the scrubber will be in much closer contact overall. In theory, it should not be limited because of this. Beyond that, being a biologist, I am intimately familiar with the photosystems, but CO2 has to actually be limited for what you have said to take place and I just don't think that is happening in most of circumstances because of the above. At best, it may boost a bit of growth, at worst, it's a waste of time and money (though CO2 is cheap). But again, likewise, as you pointed out to me, assuming that CO2 is limited with scrubbers is a generalized assumption. In all, though, I suppose the people who stand to benefit the most are those who don't have adequate water volume across the screen and/or those that have very, very large amounts of light on the screen and have low KH. While I hate to bring in anecdotes, most people don't seem to have trouble growing algae--even the absolute most CO2 limited systems (like those with heavy calcium hydroxide usage). While such conditions discourage many types of algae, others have no issues.

If you do decide to use CO2, it would be the most helpful to test whether or not it is making a difference. Weighing the dry algal weight before vs. after (in multiple samples, averaging the result) would be a good start. It'd also be interesting to see if the same result could be achieved with an increase in light (assuming they aren't carbon limited) and an increase in water flow (assuming they are carbon limited). It just makes me wonder if there is a better way to go about achieving the same end-result without bothering with adding CO2.

FWIW, I'm not against you, either. I just enjoy finding things out and testing theories, as well as discussing them. All in good fun, my friend.

[SantaMonica]

How would one add small controllable amounts of CO2, besides a tank and regulator from a calcium reactor? Is there something that could be added that would slowly dissolve, similar to a calcium block?

[Amphiprion]

Actually, you have several options. If you use a pump to feed the scrubber, I'd feed the CO2 into the pump inlet or just after the effluent. If you use an overflow, it would be best to inject it at a point where the water has gained sufficient velocity (which I would say about 1 ft below the drain). Either way, you'll get more dissolved CO2. The pump method would be arguably more effective, especially if it chops the bubbles up. In any case, you'd just use a CO2 cylinder and regulator/needle valve. You would probably also want a pH controller. It is basically a Ca reactor setup minus the reactor itself.

[KansasNative]

I am placing the CO2 outlet in my overflow box, as it is at least 20 feet from scubber, which is in another room.

Going to use an uside down bell shape container for the gas so it will have even more dwell time in the overflow box.

No need for a PH controller as the water will be aereated three time before going back to main tank.

I was one of the first to sell yeast produced CO2 systems manny, many years ago for freshwater tanks, it did not sell as it was before its time (people just did not understand the correllation between KH/PH and optimal plnat growth. :cry: