Is a power CO2 reactor better than a simple bell diffuser?

I agree with Tony that a bell diffuser is very inefficient.

However I don't understand why so many people trash the sintered glass diffusers as compared to a little 12 long reactor. They claim that since the reactor is in a closed system 100% of the co2 goes into the water, while with a sintered glass diffuser the co2 bubbles just get released into the air.

I have compared sintered glass diffusers against reactors and the former come out very favorable. Two Eheim diffusers are much more effective than my 3 inch diameter 3 foot long reactor for my 125 gallon tank. What people don't understand is that the bubbles coming out of a diffuser are smaller and have a total surface area as much as 10 times greater than a large bubble fed to a reactor with a simple nozzle fitting for its CO2 feed. Also as the bubbles rise I would think they would get bigger due to less pressure. They might also get bigger due to absorption of O and N.

Right know I estimate that one Eheim diffuser is about 75% as effective as the large reactor referenced above. Two of the Eheims would blow the doors off of the reactor.

One thing I must try is Tom Barr's recommendation of feeding the CO2 directly into the input of a filter, where the pressure is less and the co2 should be absorbed easier.

Regards,
Steve Pituch

Diffusers create tiny bubbles that, as Steve mentioned, have MUCH more surface area than bubbles typically created by reactors. These 100% CO2 bubbles will immediately begin diffusing CO2 because of the lower CO2 content in the water column. Likewise, N and O2 will diffuse into the bubbles because of their lack in the bubble. When the bubble reaches the water surface, it will be mostly, if not completely, N, O2 and other gases. The CO2 will have diffused into the water.

In my experience, I have not found power reactors to be more efficient than a good diffuser. Yes, they trap the bubbles until all CO2 is diffused, but is that really necessary? Are we so sure that a tiny CO2 bubble created by the diffuser doesn't release 100% of its CO2 also? Perhaps even quicker?

Power Reactors are bulky, unsightly and require a powerhead to work. The addition of another electrical gadget to me is not worth it.

Diffusers can be well hidden in the aquarium and are easy to clean. I simply dip it for a few minutes in a water/bleach solution for a few minutes every month. Not much to it.

The glass diffusers are orginally filters design to filter chemicals.
The filter pads are placed on top and the vacuum is applied.

These a very fine sizes, they will clog and hence have some variation in their ability to diffuse if not cared for.

To improve this: place in a deep, dark corn and with good current that blows into a stand of plants at a slight downward angle. Clean at least monthly.

Diffuser disc and Reactors can be the same efficiency, a disc cannot be placed in line. If you place a reactor in line then you no longer require a power head etc or anything that is not already in the tank, I fail to see the arguement with that issue.

It can be avoided if the hobbyist choses to.
If you want to throttle the CO2 on/off, a solenoid can be had for about the same cost as a powerhead.

The easiest types of CO2 reactors are similar to the Krib's design with the gravel vac. I modeled mine after a Dupla Reactor.

You should be able to make a decent working one for 10$ or so and the cost of a powerhead.

You can make them self leveling also rather easily as well.
Simply drill a hole 3/16" at the preset level inside the tube you want the reactor to sart wasting the Gas or the "burp" level when the reactor is shut up and you still have gas entering(say if you use DIY yeast or have no solenoid).

I use a the powerhead's venturi to suck the gas after it builds up to a preset set level and then the reactor starts to grind the gas up and spits out a very fine mist similar to that of the Disc diffusers.

I'll typically use a 6"L x 2"OD tube and put the venturi hole at about 1.5" down from the top and the burp hole about 2" down.

As far as what Steve was referring to:
The negative pressure on the suction side of a pump will pull the bubbles in. When the powerhead is "off", these bubbles will escape out to the surface rather than go into the impeller and gas lock the powerhead.

The suction side also atomizes the bubble very effectively by pulling it/stretching it out and then it hits to the impeller blades and shreds it.

The Turbofloator venturi Skimmer does the same thing.

Speaking of venturis, they work great for gas diffusion also.

Regards,
Tom Barr