Re: Barr Report - Issue 10 - CO2 - Try this.
I've read anywhere that gas bubbles in reactors or when they leave a diffusor disc soon turn into pure O2. Since there is a lot of pure O2 in the water due to plant photosynthesis and since we don't know nothing about equilibration of tiny mist bubbles I thought this might be possible. Isn't air O2 level irrelevant here?
The only pure O2 is from the plants, the rest is a mixture of gases.
That's likely why I had the samples depress the pH, there was some CO2 in there also.
Also, there is not a lot of O2 in the water really. 12 ppm is not much.
I have pure O2 that I can add to a tank and have numerous times.
It's some very stubborn stuff to dissolve. There is virtually NO Mist produced when you use O2 gas also.
How high in terms of %O2-saturation are your tanks going to develop at most?
O.k. as you have said what matters is the final result. I'm injecting CO2 through a very efficient italian device from Aquilia (a nice looking glass diffusor with suction cup, comes in three sizes, not too pricey though) and directed a small power head 90° towards the rising mist. I can confirm that the plants start bubbling around 1-1,5 hrs after lights come on and plant response is indeed incredible (much more perling than before).
So based on your observations, is this a good method that deserves some investigation?
Given that folks have a substantial amount of CO2 issues.......
I'm not sure how high you can go with O2.
I ran things at 180% a few times. Algae laughs, perhaps at 200%, then things start to crash due to O2 toxicity.
But who knows in a planted tank.........
You'll note I do tend to push the limits of each nutrient, O2 is a nutrient in a sense.
Also, the rate of degassing also increases as ppm increase in the water. A tank with 500% of CO2 vs 150% will degas faster given the other factors are the same.
As you approach the 100% level, then it tapers off slowly.
I have observed the same thing as you though, many folks now have since I suggested this. The basic question is why.
1. Some increase in the diffusion efficiency/response time can be suggested. This can be measured via CO2 levels.
2.Some increase due to O2 levels(how come the O2 is produced sooner and more of it?) but the growth is different than merely putting non CO2 bubbles all over, we can do that or even use air which has very low CO2, but still some.
So doing the dissolved in solution O2 and CO2 differences leaves the main suspect, the gas phase CO2 isolated. I'm assuming that with the disc mist method, the gas is relatively pure.
We can run the CO2 gas source through a GC and also see about the external reactor gas mixtures as well as the source itself.
Still , how does the gas dissolve from our CO2 sources in reactors/disc, but when added to the tank and through the plants with this MIST idea
causes such pearling?
Seems we cannot have both cases occuring simultaneously.
Adhesion of sticky hard to dissolve gas bubbles cannot account for this.
Even if they are hard to dissolve bubbles..............say O2, where did that O2 come from and how could it increase the O2 levels inside the tank if that is the only source of O2?
Some O2 diffusion INTO the bubbles can occur. Much like the diffusion to the air above when it degases.
But is the dissolved CO2 also not doing this same thing and at a much higher concentration than O2 gas? (CO2 is at a much higher ppm than O2)
Still, the bottom line is that folks get more pearling, better growth, less algae.
It might take awhile to figure out what is occuring still.
Do you think it's better growth or something else?
Do you think something significant is occuring in terms of the plant's growth/health?
Keep doing this method for a few weeks.
I've gotten some awesome growth after large water changes using the same temp water from tanks. The exposure to air allowed the plants to take in lots of CO2.
But this effect is shorted lived(one day maybe two).
The CO2 mist allows this same effect to keep going day after day.