DIY CO2 cannot be diffused successfully because the
pressure needed to run an adequate diffuser must be much higher than the
yeast generator can produce.
Alex

First thing to say is that I'm new to the whole Aquarium thing (2 months) so
please be gentle when replying as I could be talking through my Arse (Irish
for Bum).

Alex, are you saying that a DIY CO2 setup cannot produce enought pressure to
blow through an airstone? From my home brewing experience I know that not
only can CO2 do this easily, but it can also shatter glass bottles or blow
corks out of well sealed bottles (hence the wire around Champangue corks).
If the CO2 was not able to force its way through the airstone then Rick
would not see any bubbles.

I must admit Rick, that I am in a similar position to yourself. I have a DIY
CO2 which is connected to an airstone positioned in my (in tank) filter,
just at the up take for my powerhead (Juewl Rekord 120 tank). My tank looks
like the inside of a shaken pop bottle, with lots of tiny CO2 bubbles
diffused around it. The smaller the bubbles are, the longer it takes them to
rise to the surface, hence the longer I presume it gives the CO2 to disolve.

check out my tank at http://www.mcconnellhousehold.com/Main.htm Please bear
in mind that this is my first website & my first tank.

I too have seen no real change in my PH. I hade taken this to be, that the
acid generated by the desolving CO2 was being neutralised by the KH buffer
in the water. I expected to see my KH drop and then my PH drop. My KH is
dropping slowly, but this is probably not helped by me doing 25% water
changes 1/week. My tap water is PH 7.2 KH 6

I think the advise regarding starting with a small amount of yeast is that
you get a slow build up of CO2, rather than one big bang as it were. The
yeast is multiplying so eventually you will probably end up with the same
saturation of yeast in the mixture.

I don't know if any of this makes sence

All the best

Dave Mc