Here's a link to a yeast method that involves adding protein powder and a somewhat unique recipe:
You can find the original article on the AGA's website (link is in the thread posted above)-- although it opens as a powerpoint presentation so you will need PP to read it.
I've had the best luck with this recipe-- it produces more co2 for longer than anything else I tried.
On your setup, you could have a couple of other problems that no one has mentioned yet. Are you using airline tubing or co2 resistant tubing? If you're using regular tubing, then the gas may be escaping before or after it enters that second bottle. How much tubing are you using? The further the distance between the place that produces the co2 and where it enters you tank, the greater the likelihood that some or all of it will escape.
On yeast-- fresh yeast works differently than dry yeast, but I'm not entirely sure how. I know that my breadbaking books all specifically call for dried yeast, not fresh. I haven't seen anyone using fresh yeast in DIY recipes. I've had the best luck with dry champayne (sp?) yeast, compared to dry bread yeast. YMMV.
Finally, are you sure that your DIY system doesn't have any leaks in it? And it may be that you need to shop for a shorter juice bottle to serve as your co2 generator. Personally, I think that the Hagen units are much less hassle than rigging up a DIY system, and they have worked great for me.
In your shoes, I'd get the hagen unit. It comes with a setup that you can hang on the back of your tank, co2 resistant tubing, and a ladder diffuser. Spend $20 and I suspect you'll be much happier with your DIY system (don't use those packets, use the nyberg recipe, scaled down for the hagen unit. By Hagen unit, I mean this: