Shrimps don't eat much that you'll see, the only time you'll see them pile is when there is not enough biofilm. Don't worry they are eatingkor4ever, The yeast nutrient is from a home brew store. It was surprising how many there were, one was about 5 miles away.
There are different types of nutrients, this is called Super Ferment, 2 oz for $1.69. The local brew store had bins for several types but only stocked this. It came in a 5 gallon pail, sold by the oz. The different yeasts are bout 65 cents to $1 for 2 oz. He sells CO2 tanks and refills there so when I get my big tank and a pressure system, I'll need to know him anyhow.
Kelly, my very first attempt at CO2 was using the gelatine and it went for 52 days using a full recipe of gelatine (solid) and only baking yeast. I had to stir it up a few times, so then began cubing it, but then it won't all fit in the bottle and allow enough water to run well. So, I've been tinkering with this since December.
When I get to the end of playing around with this, I'll switch to a gallon jug and use the full amount, but first I need to change out my filtration as that is the limit on the system now I think. Now I can never get the pH below 7.6, well sometimes 7.4, and I figure it is the Pengin HOB filter. I removed the biowheel and keep the water level high but it still drives off a lot of CO2 it seems. I start at 8.2 and so 0.8 or 1.0 pH drop may be the most I can get anyways, I don't know. With less than 2 wpg, it might not be that critical anyhow. My plants bubble now at least in the top half of the tank, so I'm happy enough.
If I can get the Hagen system mix figured out to last a full month for the 10 gallon and the 20 gallon, and a good 4 to 6 week mix for the 29 gallon, well, I just may have to find something else to work on. Heck, maybe the stock market will be fun again.