Membrane CO2 reactors

[vic622]

Has anyone seen or used a membrane-type CO2 reactor?

I saw this CO2 Double Membrane Reactor Aqualine Buschke on All-Aquatics website

and it sounds like its just a strip of GoreTex between the CO2 inlet side & the tank water.

There is a single-membrane style rated to 50gal and a double-membrane rated to 100gal. I wonder if this would diffuse the CO2 better than Japanese-style cintered glass cups?

So I was wondering if a guy could take an old coat and do a DIY version ... ?

Just a thought,

Vic

Edited March 24, 2007 by vic622

[Toirtis]

Interesting...no idea...give it a try and let us know.

[vic622]

Well I picked up some GoreTex from FabricLand, now I just need to rig up a bell-jar of some sort to see what happens.

I keep y'all posted.

Vic

[jvision]

There are all kinds of CO2 diffusors out there. I have found that one of the easiest and most effective ways of getting CO2 into my tank is to bubble the CO2 into the intake of a powerhead. If you buy a little screw-down valve and put that at the end of your CO2 line, then dial it down so that just small bubbles get into the powerhead, you'll have a fine mist of CO2 in your tank.

[vic622]

Update:

Well I put together a unit using a small plastic juice bottle (for lunches), a threaded/barbed fitting and the center cut out of the lid (think of a Mason jar).

I filled the bottle about 1/2 full of old ~4mm pebbles, attached the CO2 line and put the membrane material in place, held on by the lid.

I'll need to add more pebbles, it wants to float.

There is a small stream of bubbles <1mm of CO2 from one location on the membrane, leading me to think there is a very small pinhole at that location.

I'll try a new piece on the next days off, and I'll post some pictures.

It has promise, but I think it needs a bit more tinkering.

Vic

[Tanker]

Not sure how relavent this may be... but is CO2 heavier or lighter overall than atmosheric air mixture? Reason: depending on your jar, you may wish to reduce it's volume signifigantly using filler so that the CO2 doesn't sit under the atmospheric air and force it out, first.

If your CO2 source produced 1 cubic inch per hour, just to use some numbers, and a 6" high jar with a 3" diameter is used then even half full of sand it would have approx 21 cubic inches of atmospheric air. Which means that switching to this method could meana total loss of any Co2 from the tank for 21 hours while it's forcing out atmosphere (and you would only see bubbles...). If Co2 is lighter, then problem solved... which is why it may be an interesting thing to check on, prior.

[happeboy]

I believe that co2 is slightly heavier then the majority 02 n2 mix of the atmosphere. But I dont believe in a system with movement that it would settle out into layers. You would just be pushing out a diluted mix of co2.

But it has been awhile since I've done mush chem.

Edited May 27, 2007 by happeboy

[vic622]

Just thought I'd finish this off with an update & observations ...

The idea seemed good but the implementation not so good

I used a small screw-lid bottle (about 100ml) and filled it about half-way with sand.

I cut the inner portion of the lid out so that it looked like a mason jar lid without the glass.

I then used a small threaded/barbed fitting for drip irrigation, cut a hole (~1/4") and threaded the fitting in along with a bit of silicone to seal it CO2-tight.

I cut a piece of the membrane that was over-sized for the hole in the cap and very carefully installed this and the cap.

Trial - 1

Even with the sand the contraption wanted to float as soon as the bottle filled with CO2

Trial - 2

Completely wet the sand and filled the bottle with water and retried - Success! :thumbs:

Problems!!!

No matter how careful I was installing the cap/membrane there always seemed to be at least 1-2 larger holes where the CO2 came out at a faster rate. This stream of bubbles (~1-2mm diameter) were obviously larger than desired.

Conclusion

I think the membrane was the culpret as the larger holes were often in the field of the membrane, not close to the edge/lid. I believe the quality of the membrane was not consistant and so there were thick and thin spots, throughout. If I could find a good section it would work as I observed micro-bubbles in other areas of the membrane once the bottle developed some pressure.

The biggest problem with further experimenting was the time to change and reset the rig. If I was using a CO2 tank instead of DIY, it might have gone faster, though.

Finally, I took the contraption out and used the barbed fitting to feed the CO2 into the bottom of my quick-filter on an Aqua Clear power head - Works great.

Happy-planting,

Vic