vic
Fish Crazy
Do a search here or on fishgeeks.com for a DIY CO2 setup. Easily done, no cost and will likely work as well if not better than the e-bay one. If you do go DIY be sure to use either a champagne yeast (from wine making store or brewers yeast. They a far more alcohol tolerant than other yeasts. You will likely discover on, doing the research on the DIY, that a yeast based generator will not likely support a 125G tank. Do the e-bay thing again and have a look at CO2 regulators. You should be looking for one with 2 gages, a bubble counter, a metering valve and a solenoid. Should be in the $65 to $85 range. This will not include a tank.
Cheers;
Cheers;