there is debate of what is the best way to do co2, what is pretty much agreed is that pressurized is the best way to go. a 5lb co2 tank u can find for $55 ish and a regulator u can find for about $100.
there are cheap regulators out there too, they do work, but are hard to dial in and they tend not to work well with diffusers that require high pressure.
now there are regulators with solenoids, so u have to plug it into an outlet for it to work, but u can put it on a timer, to turn it on and off with ur lights or somthing.
i am personally on the side of the debate that believes that the pH fluctuations will be greater with the co2 constantly going on and off night after day after night, so i do not like regulators with solenoids.
so i personally got a tunze regulator i think it was 7707/3? or somthing like that.... it is really simple to use, easy to set, and it keeps a stable bubble count no matter what diffuser ur using.
btw, with 35 gallons, i think a DIY thing might not work with a big size like that
Last edited by ajlee613; 09-12-2012 at 08:49 AM.
Reason: extra info