ok heres what ive tried.
Sintered Glass Rock (Ehiem Substrat i think) wedged and expoxied into half a check valve.. bubbles started fine but it soon changed into an airstone.
ciggerette filters, both sizes small and large.. they work for a while but dont really give me much desire to use them as they do the same as sintered glass.
various woods ive tried.. but not consitently tried, i think if someone used a peice of wood they should silicone or epoxi the sides so the co2 only escapes from the tips of the grains.. if that was done you would have pretty fine bubbles i think
Ceramic from a china cup handel which i epoxied into another half check valve. no air escaped i think the pores were to tight in this perticular ceramic.
reactor out of a gravel vac.... use to blow the sponge out and look a sight ugly in the tank.. not bad operation but you need to get the right sponges and the right gph pump for it to be best effective..
ive tried a ciggy filter into a powerhead to chop the bubbles even more.. this made one of my plants release a few bubbles from one leave which i was happy about but it also lost loads of co2 to the surface..
the gas strainers from inside gas ciggy lighters.. this was just like an airstone.
at the moment i have taken one of those nylon back scrubbers.. there like nylon webbing like you get fruit in.. they basicaly twist them into a plant and tie them and sell them as loufers
i cut one up and took a sheet of it and stuffed it into an inch diameter polycarb tube which is about 11" - 12" long, a bung in the top and a canister outlet later i found the co2 gets quite stuck in there and this morning the co2 was all dissolved from inside.. i dont thimk it escaped as there was still 1 or 2 bubbles.. its quite small aswell.. ill post pics later
what about everyone elses experiences on this.
light is a very important factor in keeping a planted tank.. but if you use co2 so are the diffusion options lol
i havent got any choice for anything descent over here (UK) and co2 isnt really taking off at my lfs's so i need to find my own way. i think ceramic is the best but its finding some sutibly porous enough to be nice and effective..
i want to run the co2 into my canister but i cant think of anything other than an extremely fine diffusor to stop my canister airlocking.
anyways your experinces ladys and gents