I usually just measure by eye and color, so I don't have an exact recipe, but I make a few variations on gel food for my bottom feeders and shrimp.
For the most part, I use powdered spirulina, powdered chorella, ground algae wafers and ground ken's veggie sticks... and I also sometimes use liquid marine algae, frozen cyclopseze, baby brine shrimp, and hikari first bites powder. oh and baker's yeast. and of course gelatin.
I don't make it with ALL of the ingredients every time. I mix it up each batch. I make up a liquid but thick, dense bowl of gelatin, and set it aside. Then I grind all my dry ingredients in a mortar and pestle. I take the dry ingredients, any cyclopseze or shrimps, and start to mix it in a bowl, slowly adding gelatin liquid until it's like caramel consistency. I then pour it into silicone ice cube trays, the ones that are long and skinny for water bottles. I let it sit for 1 hour, and then put it into the freezer. 24 hours later, I peel the sticks out of the tray, and keep them in a ziplock freezer bag.
Having it in stick form is great for me, because I can put a tray of small stones in the oven at 200º just to heat them up, and I press the sticks onto the stones, like a wax stamp or craypa. I pretty much paint on the algae, until it gets too sticky to add more. Then back in the oven for 10 minutes, or until the algae is completely crusted over. Bottom feeders and shrimp go nuts over the rocks. A lot of the smaller fish also seem to love the debris that float off the rocks into the water column. It usually takes about 4 hours for a rock to be completely dissolved, but it's usually eaten much faster than that.
So, I pretty much make food every 2 months or so, and bake rocks once a week. If I run out of rocks, I will cut off a 3/4" chunk of the frozen stick, and wedge it into a tiny candle stick holder, which sinks. Sometimes I think this is their favorite way to eat, the gobies pretty much bathe themselves in food when I do this.