use one with a high middle number(right? I don't think its the 3rd number) that is liquid soluble and you can probable use about as much as you want as long as it's mixed with the correct amount of water. Miracle Bloom Booster is a good example, but I am trying to break away from miracle grow and give smaller companies a bit of help. How do you make fish emulsion? Is that the poo? Or is it all the fish or what?