Here is the best way I've found so far to dissolve Co2. it's similar to, but not as inexpensive as Tom Barr's viewtainer method. but its a heck of a lot easier, but a bit more expensive and everything is available at your local fish store.
Pictures are worth 1000 words so you could skip everything below and just look here:
http://artw.myvnc.com/gallery/view_album.php?set_albumName=album52
parts needed:
1 maxi jet 400 powerhead
1 small size gravel vaccum tube, the one that is slightly over 12" long with a 1/2" hose
1 drill bit
some silicone if you drill the hole too big.
1 aquaclear mini sponge
instructions:
1. Take the power head out of the box and throw away everything except the intake strainer and the black airline tubing, and the suction cups.
2. Remove the PVC from the python vaccum tube and throw away
3. drill a hole in the top of the gravel vac, in the green part, smaller than the diameter of the black airline.
4. insert the black airline, the tighter the better but if you drilled the hole too big silicone it and wait 24 hours.
5. Insert the powerhead into the gravel vac tube as shown on the attached pics.
6. apply the suction cup bracket and the intake strainer into the powerhead.
7. Cut the AC sponge so its sort of round and insert it into the business end of the gravel vac.
8. Install into aquarium, hook up the co2 and have fun.
Pretty much the same one I used ... except I didn't use an AC sponge as it is a little too dense and could get bound up with nitrifying bacteria .. clogging the reactor
An Eheim pre-filter - a la Treatise on CO2 method - prevents that
Thanks guys. It so happens I've been fooling around with this type of setup for some time, trying to get it just right - or at least better.
I tried it with the tube vertical, but even with a sponge in the end like Art suggests the force of the powerhead would often blow the bubbles right out through the sponge. Or blow the sponge out of the tube. And the sponge also tended to get loaded up with stuff and go green.
I tried it with the tube not-quite-horizontal, which greatly increased the amount of time the bubbles spent inside but minimized the dispersion factor because the bubbles weren't trying to rise against the flow and getting dissolved.
So after reducing the output of the powerhead and removing the sponge at the end of the gravel vacuum tube, I *finally* ended up with pretty much the same as Art: a constant and even attractive silvery effervescing swirl of bubbles inside the middle length of the tube. Couldn't ask for better dispersion (but I could ask for a spare $300 for a CO2 tank & regulator & check valve, etc.)
I really do need a check valve, though. And a stop valve for easy re-charging of the CO2 generators. And Art's rig is way more attractive than mine!
Given the interest lately in DIY CO2, I thought other folks might be interested in what I've come up with...
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