Addition of CO2 ?

[KansasNative]

Found this comment from a professional grower:

I grow algae for a living in the Pacific Northwest. We have to use artificial lighting and in fact promote growth with a 24 hour per day light dependent cycle. Thus we must disolve CO2 into the cultures semi-continuously as needed. Artificial light will never replace natural sunlight and the amount of energy spent on electricity for lighting versus compressed CO2 is tenfold.

Thoughts ?

[KansasNative]

[attachment=0:29v7s1n5]Algae Matrix2.JPG[/attachment:29v7s1n5]

[kcress]

Thoughts?

None! Since so little information is provided. :lol:

[whites]

seems right there is a thread of where a guy (sorry dont know your name) who used a venturi on the scrubber to suck in air and has found good results where there is a "foam" on the screen.

[KansasNative]

Whites, did you want a doctoral thesis on the benefits of CO2 for optimum agal growth ?
I understand you want specifics, I do as well. I apologize for not providing more data. ops:

Not trying to be difficult here, just want to know if you think the benefit is worthy of cost and effort.

CO2 works for higher plants, so why not algae. :mrgreen:

I think I might try it as I do have the equipment: CO2 tank, high pressure regulator, bubble counter, PH monitor,
diffuser and misc stuff.

Might be awhile, as I have so many projects and hobbies. I am retired, but I am busy with the things I never
had time for as when I was an electronic warfare signal intelligence analyst, Russina linguist, weapons expert
and covert operations helicopter pilot. :P

[SantaMonica]

One holdback for CO2 in a reef is of course pH. Keeping pH up to 8.4 is one of the major battles of a reef tank, since 8.4 gives you the most coral calcification (growth). Many reefers go out of their way to remove CO2 (including using algae scrubbers ). And sure enough, many are new experimenting with CO2 scrubbers (which really messes with my forum keyword searching on other sites.)

Any injection of CO2 drastically drops pH, and once below 7.9 or so, some tank inhabitants may start feeling ill. Don't know how important pH is for SW FOWLR, however.

[KansasNative]

Yes I thourghly understand the need to keep the PH in the upper range. My tank is freshwater, but its inhabitants require a high PH as well (over 8.0). If you know the KH (carbonate hardness) you can adjust for PH and still keep the CO2 level in the approxmately .8 mg/L range. There is a table for this, if you don't continously monitor PH.

Simply add CO2 to scrubber input (source water) (not main tank) for growth and then release it on the down side. Simple way is to release CO2. Just aerate the water after it interacts with scrubber or prior to return to main tank.

I would think this premise would would work for saltwater also. Would it not ?

Most folks aerate a freshwater tank thinking it adds oxygen, but it does not, it just releases the CO2.

You all, aerate your saltwater anyway, don't you, (protien skimmer) or just to add O2 or ?

[Amphiprion]

Aerating a tank will add or deplete CO2 and O2 and will settle in equilibrium with the surrounding air, dependent upon the solubility of each and the partial pressure of each in both media. CO2 is much more soluble in H2O, so it will equilibrate with a higher overall concentration compared to O2, but you will get solubilized O2 along with it unless the tank is saturated or supersaturated with respect to O2, in which case it would lower it. Planted tanks or tanks with lots of photosynthesis may note a net lowering effect on O2 from vigorous aeration. Tanks that don't, on the other hand, may notice an increase. CO2 should hopefully lower with aeration, but only if the air's partial pressure is lower.

Saltwater tanks will get their O2 from skimming and photosynthesis. Kalkwasser will also rapidly deplete CO2 concentrations.

[KansasNative]

OK and ?

So injection of CO2 into source water will be of a benefit for agal growth and if aerated after scrubbing will not be detrimental to tanks PH.

[Amphiprion]

Shouldn't be as much of an issue if aerated afterward. If there's enough going in, you'll still notice a slight change, but it won't be dramatic. One last thing is that I don't see CO2 being as much of a limiting factor on a scrubber. Most have enough atmospheric exposure, even when the flow isn't pulsed, that it shouldn't be limiting, which is one of the advantages to using a scrubber. At this point, for most folks at least, I am betting that light is still the limiting factor. The higher pH/KH environment may also tend to select for algae that can utilize bicarbonate to fulfill their carbon needs. Of course, this is just a plausible prediction based on various factors. CO2 may still be limiting some scrubbers in certain situations, but how many actually do require added CO2 is unknown. I don't think it will be an issue for the vast majority of folks because of the way scrubbers are designed, especially vertical ones, with maximization of surface area and thin films of water. By virtue of the same principle, I also see you losing at least some of the CO2 you add (maybe a lot?). This is all more of a guess/hypothesis, so take it at face value.

FWIW, the main point of my previous statement was to note that aeration does add oxygen in many situations contrary to what you had said earlier.