Excellent DIY CO2 diffuser with no work (now with *pics*)

[Guest]

No, this setup bleeds tiny bubbles and maintains good Co2 levels, but I want to set your method up in my little 5 gal so that I dont have to have a large vac tube taking up space. I can live with the cavitation noise for the small tank in my computer room.

 

[7Enigma]

No, this setup bleeds tiny bubbles and maintains good Co2 levels, but I want to set your method up in my little 5 gal so that I dont have to have a large vac tube taking up space. I can live with the cavitation noise for the small tank in my computer room.

Got it. I think the method in the OP is perfect for the small tank, very little clutter and just as good IMO as the powered reactor with gravel vac.

 

[Guest]

But getting back to the question I asked about leaving the gravel vac tube on for ultra diffusion. Say you took your Co2 line into the intake on the PH, even somehow diffused it there with a small stone. Then wouldnt the PH force an almost immediate diffused Co2 gas into the vac tube and out of the filter in front, then the vac tube captures the un-diffused portion of Co2 and traps it, causing further diffusion to almost 100%? Looks good on paper anyways. Dont mean to get off the OP, but the idea sparked another.

 

[Thebluyak]

thats a great idea, I think I might just move mine out from my intake and get a power head, I need one for my tank anyway to create some current

 

[Zezmo]

What you have described is the mist method of CO2 as discussed elsewhere. My recent "behind the scenes" post shows a few pictures of this in action in my main tank. For my setup I use a ceramic (ADA) type diffusor/airstone to bubble the co2 into the powerhead intake. The impeller really chops those bubbles up. Every inch of the tank becomes filled with these micro bubbles.

Please note that I am of the belief that VERY quickly (less than 5 seconds) any CO2 bubble present in the tank has equilibrated with the tank's CO2 ppm level, and that these are not in fact CO2 bubbles that are flying around attaching to plant leaves and giving a high level of CO2 directly on the leaf surface. This is sound belief due to diffusion rates and CO2's solubility profile, and most importantly the small size of the bubble offering vastly larger surface area to volume ratio as a normal size bubble.

I find this comment interesting. I personally could not confirm or deny that hypothesis. Some empirical observations for me are that while the actual "measured" CO2 in the water is similar to other methods I have used. My CO2 injection rate (bubble count) is much higher, and my results much better with mist. The plants/algae act as if there is more CO2 available that the measurement indicates. Of course this could also be due to better circulation presenting a steady supply of nutrients/CO2 to the plants.

Even if the bubbles are equalized to tank CO2 ppms, then these are still CO2 enriched bubbles (as compared to atmosphere) and should still provide direct benefit to the leaves they stick to. A stuck bubble by that hypothesis should continually equalize to tank PPMs. This would have a net effect of increasing the leaves surface area for CO2, due to the hemispherical shape of the half of the bubble that is in contact with the water.

That said, I am not convinced as to whether equalization takes place that fast or not. What I am saying is that either way the net effect on plant growth is the same. Pure CO2 bubble, or equalized bubble, you are still ramming CO2 down the plants throat.

 

[7Enigma]

But getting back to the question I asked about leaving the gravel vac tube on for ultra diffusion. Say you took your Co2 line into the intake on the PH, even somehow diffused it there with a small stone. Then wouldnt the PH force an almost immediate diffused Co2 gas into the vac tube and out of the filter in front, then the vac tube captures the un-diffused portion of Co2 and traps it, causing further diffusion to almost 100%? Looks good on paper anyways. Dont mean to get off the OP, but the idea sparked another.

If the PH wasn't as efficient as it is (or at least mine is), then I'd say yes/maybe. As it is, however, the bubbles produced by just the PH alone are so small that with the current they take a LONG time to reach the surface. Normally they get shot close to the substrate and then move to the other side of the tank and some come back around before they reach the surface. I think the difference (if any), that someone going to build a reactor right now should probably not need the gravel vac tube, but if you don't want to remove it, and don't mind seeing it in the tank, there is no reason to remove it.