LOL, MG. I could totally see myself thinking they were goldfish crackers and eating some before thinking it through.
Uahua, I am going to buy some clay this weekend, if you want to try it out, let me know and I will gladly send you a smaller portion. They do sell it in smaller sizes, but it's more expensive per pound.
Wallace, keep us updated!
DF - this is quite simple. It's a recipe, ultimately. Think of a cake: you put in flour, eggs, sugar, milk, flavoring, etc. Each part of the recipe has a set amount of calories and if you total up your calories and divide it by the number of slices, you'll know how much a piece will be within a small percentage of error. Same thing applies to this method. If you know the starting out numbers, you can do the same thing. In fact, you could make it really technical and weigh each piece as you make them so that you have the same amount in each tablet. However, you can be a less stringent, weigh the entire end product and one tablet. Then just do a little math to find the range. Completely unnecessary in my opinion unless you want to market these with a set amount of chemicals. They work and quite well for the hobbyist. You get the benefit of the added clay and you don't have to spend a lot of money on them. It's all a matter of preference.
Make the gel caps, make the clay, make frozen dirt balls or buy the commercial fertilizers. Makes no difference to me. I'm just putting this up here as I've had many pms over the past year or so asking me how I make them. I figured others including those that aren't currently registered (just lurkers) will also be able to see the process if I created a thread.
Bottom line is I've had more success with this than any other method of fertilization, but this is solely based on my personal experience/needs. Most of my tanks are only fertilized through the substrate, with the exception of the one filled with java ferns. They are getting supplemental water ferts on an occasional basis.
Without Algae, death of mankind would be inevitable.